Having won various Finnish Karting championships including the ICA Junior title in 2004, the ICA Viking Trophy in 2005, the Formula A and ICA titles in 2006, not to mention the 2006 WSK International Series Formula A title, by 2007 Valtteri was ready for the move up to single-seaters.

In his debut season, the Finnish youngster made an immediate impression, finishing third in the Formula Renault 2.0 Northern European Cup with Koiranen Bros Motorsport and winning the Formula Renault 2.0 UK Winter Series with AKA Cobra. Sadly, though he won three of the four races, Valtteri wasn't eligible for the title because he didn't have an MSA-registered licence.

In 2008 the Finnish youngster continued in the Formula Renault 2.0 Northern European Cup while also contesting the Formula Renault 2.0 Eurocup. In a tour-de-force season with Motopark Academy, Valtteri won both titles, winning an astonishing 12 races in the 14 round NEC and 5 rounds of the Eurocup.

His meteoric rise through the ranks continued in 2009 when he moved up to the Formula Three Euroseries with ART Grand Prix. Though he didn't win any races he finished third overall in the championship with six runner-up finishes and pole positions at Lausitz and Brands Hatch.

He also contested four races in the British F3 Championship, though he was ineligible to score points, and finished fifth in Macau.

On 29 January, Valtteri was confirmed as official test and reserve driver for the Williams F1 team, despite never having sat in an F1 car before.

While former Williams test driver Nico Hulkenberg moved up to a full F1 race seat, it was also confirmed that Valtteri would contest the Formula Three Euroseries with ART Grand Prix.

Despite a strong season, which included two wins and six further trips to the podium, Valtteri could only mange third in the standings, finishing 27 points behind Edoardo Mortara. In addition to his Euroseries exploits Valtteri finished third in the Macau Grand Prix but won the Masters of Formula 3 at Zandvoort, becoming the first person to win the event twice.

Retained as official test and reserve driver by Williams for 2011, Valtteri contested the GP3 Series with ART Grand Prix. After a tough start to the season, he claimed a win in each of the last four race weekends and secured the title by winning the penultimate race ahead of his team-mate.

Having secured the GP3 title, weeks later Valtteri contested the Donington round of the British F3 Championship with Anthony Hieatt's Double R Racing, his win in the second race securing him seventeenth in the overall standings.

Despite not making any appearances for Williams during the 2011 season, Valtteri was soon on the pace in the November Young Driver Test, posting the tenth quickest time. Weeks later, the youngster was confirmed as test and reserve driver for the Grove outfit, with Frank Williams assuring the Finn of at least 15 Friday sessions over the course of 2012.

Sure enough, Frank kept his promise and Valtteri took part in the Friday morning session in all but the Australian, Monaco, Canadian, Singapore and Austin rounds.

Other than a heavy schedule in the simulator, Valtteri also took part in the pre-season test in Barcelona and the mid-season test at Mugello and Young Driver Test at Silverstone.

On 28 November, it was confirmed that in 2013 he would move up to the race team, the Finn joining Pastor Maldonado. With some sections of the media pushing Valtteri as the next big thing, it was hoped the FW35 would allow him to prove them right.

Unveiling the FW35, Frank Williams, described it as a "step forward from last year's car", he was to be proved comprehensively wrong. Indeed, the FIA almost immediately declared the exhaust illegal, sending Mike Coughlan, scurrying back to the drawing board.

"The Coanda effect is going to be a big thing for us," he'd said at the time. "There's been no rule clarification concerning this area of the car, so we'll work closely with Renault to maximise the available gains."

While both drivers seemed happy with the car in pre-season testing - and where the rules are not so strictly applied - it was an entirely different matter in Melbourne where Maldonado described the car as "undriveable" and warned the team had set itself "back a couple of years".

Interestingly, despite having had no racing in 2012, Bottas was very quickly up to speed in Melbourne, making it through to Q2 - unlike Maldonado - and eventually finishing the race 14th, whereas his teammate spun off after just 24 laps.

In Malaysia he was just outside the points, while in Canada he was to qualify an amazing third, only out-paced by Vettel and Hamilton.

Though his pace was obvious, the FW35 simply wouldn't allow him to put it to good use. The fact that Maldonado's average qualifying position was 16th and Valtteri's 15th says all you need to know about the car's single-lap pace. However, in race trim the FW35 was no better.

Though reliable, with only two retirements, one KERS and the other hydraulics, the car was a dog, Maldonado scoring just one point over the course of the season and Valtteri leaving it until Austin before he could finally open his account.

For 2014, having previously announced that it was to switch to Mercedes powerplants, the team opted to retain Valtteri and partner him with Ferrari veteran Felipe Massa, the Grove outfit going for a mixture of youth and experience.

From the outset, it was clear that the FW36 was competitive - and not merely due to the Mercedes PU106A Hybrid in the back. While 2014's remarkable resurgence was mainly due to the decision to switch to Mercedes power units, a number of other factors were involved, not least the numerous changes to the team's technical and management line-ups.

From the first race Valtteri was in the points, passing numerous rivals twice on his way to a convincing fifth, albeit having made things all too difficult for himself when he needlessly clouted a wall as he worked his way through the pack having started 15th and therefore having it all to do again. Though he was to subsequently experience a comparatively lean period, by Austria he was one of the true stars of 2014.

There were further passing heroics at Silverstone when he carved his way through the field, having started 16th, to finish second.

As Williams built up a head of steam, so Bottas delivered, taking four podiums from five races in a sequence that extended over the summer break.

Whilst his teammate suffered a mixture of over enthusiasm and bad luck, Valtteri got on with the job, and deservedly, alongside Daniel Ricciardo, was seen as one of the true stars of 2014.

Finishing fourth in the championship, 52 points clear of Massa, in 2014 it was easy to see what Sir Frank had always seen in the Finnish youngster.

That said, whilst the Finn is regarded, alongside Ricciardo, as one of the great revelations of 2014, we felt it would have been good to see him occasionally emulate the Australian in the smile department...

Those who thought Williams' third place in 2014 a fluke, were no doubt more than a little surprised to see the Grove outfit repeat the feat a year later. Admittedly, the British team wasn't as convincing as 2014, and in many ways must be considered merely the 'best of the rest' behind Mercedes and Ferrari.

Whilst the FW37, like its predecessor, starred on low downforce tracks, it struggled pitifully on slow corner circuits - such as Monaco - and in the wet. In Hungary, one of the most notorious slow tracks on the calendar, the Grove outfit came away with nul points, whilst Red Bull, came away with its biggest haul of the season.

Valtteri, whose early races were overshadowed by a back injury incurred in Melbourne, wasn't nearly as impressive as we'd hoped, and perhaps this is why Ferrari opted to retain Kimi Raikkonen at a time most were convinced the Williams starlet was to partner Sebastian Vettel in 2016.

Of course, other than the fact that the FW37 was clearly only suited to certain tracks, Valtteri's chance to shine was also compromised by the resurgence of Ferrari and Vettel.

Admittedly, he led the German home in Bahrain and Raikkonen in Spain and Canada, but for the most part was forced to battle with 'the rest'.

Other than some poor starts - though nowhere near as bad as teammate Massa - Valtteri was involved in more than his fair share of incidents, though it would be unfair - particularly when it comes to his tangles with Mr Raikkonen - to place all the blame on his shoulders. However, the fact is, Valtteri got himself into situations he needn't.

There is no doubting that Valtteri is a very good driver, but is it that missing 'special element' that led Ferrari to pass on him?

Too often in the past we have seen drivers dazzle on their debut, continue to impress and then hit some mystical barrier which seems to halt their rise through the ranks.

At the end of 2015 the Pitpass jury was still out on Valtteri, unable to decide whether he is the real deal or not. A year later and we are none the wiser.

While his domination of teammate Massa in qualifying was the most undeniable in 2016, the Finn beating the Brazilian 17-4, was this more about the veteran's lack of motivation in what was to prove his final year?

Then again, while Massa had the stronger start to the season, scoring 32 points to Valtteri's 19, that was effectively as good as it got for the veteran.

Ignoring the numerous shortcomings of the FW38, poor aero, lousy in slow corners and the wet - all of which takes some ignoring - in the early stages of the season when the Williams was at its most competitive Valtteri too was at his strongest, most notably in Canada when to hook his and the team's only podium of the season.

Russia, Italy and Malaysia also saw strong performances, the Finn doing particularly well to out-qualify Ricciardo at Monza.

However, there were a number of needless incidents seemingly born out of frustration, including the clash with Hamilton in Bahrain, though the Finn also suffered more that his fair share of technical issues including a suspension failure in Abu Dhabi.

Perhaps we are being overly critical, but then perhaps so were Ferrari also, for despite his dominance in qualifying, the fact that he out-scored Massa 85-53 and despite the various weaknesses of the car, we still feel that Valtteri didn't deliver as much as he could in 2016.

At the centre of the media frenzy over who would replace Nico Rosberg at Mercedes, we wondered whether perhaps a year alongside Lewis Hamilton in a race-winning car would give us the golden opportunity to make a decision on the Finn. On January 16, six weeks after Rosberg's shock announcement, Valtteri was finally named as the German's replacement.

"It's definitely another dream come true," said the Finn, "to race in another team with such great history - especially in the recent years, which have been so impressive. I'm really proud to become a part of that and grateful to everyone at Mercedes for trusting my skills and giving me this opportunity.

"I know the power unit well from the last three years with Williams. But there are a lot of new things to learn with the car and also with how the team operates at the factory, in testing and at the races."

While he might know the power unit well, it was going to be interesting to see how the Finn worked - and dealt with - Hamilton, for the three-time champ, having seen off one challenger was going to want to establish his authority over his replacement at the earliest opportunity.

Furthermore, like Nico Hulkenberg, Valtteri has long been regarded as one of those drivers considered a "potential world champion" given the right equipment.

Well, despite the regulation changes, the Mercedes was certainly considered the "right equipment", and therefore the Finn finally had the wherewithal to show what he could do.

From the beginning of pre-season testing, while the car still had reliability, there were questions marks over pace, especially as Ferrari had clearly taken a step forward.

Then there was the length of the car which led to Hamilton comparing it to a boat, though this was nothing compared to Toto Wolff's claim that the W08 was a "diva".

While the Mariah Carey issues may have continued throughout the year, a major update to the nose, front wing and barge boards in Spain made a world of difference henceforth.

Just as the W08 had good weekends and bad weekends, depending on track characteristics and weather, so the drivers' form appeared to fluctuate.

Though the W08 had been built around Hamilton and Rosberg, Valtteri was quick to get to grips with it, the Finn already familiar with the power unit.

By the third race he had claimed pole, though it wasn't until the next race (Sochi) that he finally climbed to the top of the podium.

A rare engine issue - two if you count his qualifying failure - meant retirement in Spain, but following a so-so performance in Monaco he strung together a run of five podium finishes including a second win in Austria - even if his grid getaway remains the subject of pub debate.

A strong performance at Silverstone, where he was hit with a gearbox penalty, saw Valtteri heading towards the summer break not only keeping his illustrious teammate honest but championship leader Vettel in sight.

After the break it was as if another driver was in the second Mercedes, an alternate Valtteri, and as the Finn's season slowly fell apart it was the man himself who was the most critical of his performances.

In race after race the Finn was out-shone by his teammate, who admittedly was now performing at another level. However, in a number of instances - most notably Belgium, Malaysia and Austin - he was as far off the pace as his countryman Kimi Raikkonen to his teammate.

By now, Valtteri had been confirmed by Mercedes for another season but this didn't stop the slide. Indeed, it is noticeable that only once Hamilton had secured the title that the Finn rediscovered his mojo, with a string of convincing performances including his third win of the season.

While the Finn described his 2017 season as "disappointing", perhaps he was being a little too hard on himself. Though admittedly there were weekends when he was clearly off the boil, when he was on form he was very good, and on a number of occasions soaked up consistent intense pressure when others would have fallen apart - not least fending off Vettel for that inaugural win.

Hamilton described Valtteri as the best teammate he's ever had, and while one was tempted to write this off as another snipe aimed at Nico Rosberg, the fact is that the Briton, and therefore the team, was a lot less tense than in previous seasons.

Following 2017, for Valtteri, 2018 could only go one way or the other... the fact that he was to ultimately describe the season as his "worst ever" tells you all you need to know.

Things got off to the worst possible start when the Finn crashed at the start of Q3 in Melbourne and consequently had to start from tenth.

Things improved with back-to-back podiums in the next two races, pushing Vettel all the way to the flag in Bahrain but falling foul of the safety car in China and thereby losing out to Ricciardo.

It's fair to say he was robbed of victory in Baku, where, while leading, he suffered a late puncture after hitting debris left on the track following an earlier incident.

There were further podiums in Spain - where Mercedes introduced its much-needed upgrade - and Canada, while in Germany he was firmly told not to challenge teammate Hamilton after the re-start.

While this raises the thorny subject of Valtteri's "wingman" designation by Toto Wolff, the fact is that with Ferrari mounting a spirited challenge to Mercedes dominance, the team had to throw its full weight behind its star driver.

Indeed, Valtteri's 'wingman' role was never more obvious than in Russia, when he was ordered to relinquish his lead to Hamilton, but in all honesty, by this time the Finn had yet to win a race while the Briton had won four of the previous five events.

The team orders in Sochi gave Hamilton another win, which he followed with another victory in Japan, at which point Valtteri's performance took a positive nose dive.

Though he was now clearly playing Barrichello to Hamilton's Schumacher, the Finn was nowhere near the pace of his teammate and in the final four races of the season was essentially 'best of the rest'.

At season end, despite having the same car as the world champion - who had secured 11 wins with the W09 - Valtteri had no wins and was fifth in the overall standings, behind the Ferrari duo and Max Verstappen, whose opening phase of the season was littered with reliability issues.

Though retained for 2019, Valtteri was aware that he must raise his game significantly, for waiting in the wings was Esteban Ocon, who, unable to secure a 2019 drive, was appointed test and reserve for the German outfit.

Whether Valtteri had it in him to raise his game significantly remained to be seen, for, as we had previously noted, should Robert Kubica encounter issues on his return to the grid with Williams, Valtteri could head back to Grove while Ocon - who is managed by Toto Wolff - got the seat alongside Hamilton.

The Finn got his season off to the perfect start with a win in Melbourne. Starting from the front row he grabbed the lead at the start and never looked back, and while the media focussed on the concept of Bottas 2.0, a cryptic tweet hours after the race suggested that a breakfast of porridge had proved to be the winning formula.

While teammate Hamilton took back-to-back victories in Bahrain and China, Valtteri hit back in Baku, at which point the championship appeared to be all about the Mercedes drivers. Again.

Hamilton then began a run of six races in which he claimed five wins, and while Valtteri continued to rack up the podium finishes it was clear his title challenge was fading.

Indeed, following his win in Azerbaijan, it was Suzuka before the Finn took to the top step of the podium again.

A weekend of supposed celebration for Mercedes didn't exactly go the script, for while Valtteri looked set to take second in Germany, on a day when his teammate's race was falling apart, a botched move on Stroll saw the Finn end up in the barriers, adding to his team's Hockenheim horror.

A further win in Austin, where his performance was faultless, brought his tally up to four, and though an oil pressure issue in Brazil meant Nil Points, by season end he had done enough to claim the runner-up spot... a far cry from the season before.

Though retained by Mercedes - on a one year contract - for 2020, Valtteri admits that concern over his new contract distracted him. He is adamant that this will not be the case in 2020.

Indeed, at the end of the season the Finn announced that his marriage was at an end, meaning that he can focus on the championship with no distractions.

On his day, Valtteri is up there with the best of them, and clearly he is an ideal team player as far as Mercedes and Hamilton are concerned.

Fact is, Valtteri is teammate to a driver at the very peak of his form, a driver who shows no sign of easing off. To finish second-best to a driver like Hamilton is nothing to be ashamed of.

That said, if he is to realise his dream, or at least give the Briton a season-long scare, Valtteri needs to raise his game and maintain it.