At 25, Spence was running a garage with business partner David Porter. He kept himself to himself, but he wasn’t short of steel – he’d overcome polio as a child – or ambition: he’d been a tank commander during his National Service. He was disciplined and self-sufficient. “At the time I thought he was aloof,” says John Fenning, FJ teammate to Spence and Arundell at Ron Harris Team Lotus in 1963. “Perhaps I misread it. Perhaps he was just shy. But, for me, Pete was king.”

Arundell worked wonders that season in the monocoque 27 – “the worst car Lotus ever built,” says Fenning – to secure his second consecutive title. The previous year had been a cakewalk: 18 wins from 25 starts. In all that time Spence had scored just one victory, at Reims in ’62. Even so, he made his World Championship debut before Arundell when he deputised for the injured Taylor at the 1963 Italian GP. He did a solid job, too, qualifying ninth and running sixth before his engine failed with 12 laps to go. There was more to Spence than his okay results suggested; Chapman was impressed by his calm attitude and thoughtful feedback.

Arundell was back in front by the start of 1964, though, beginning his F1 career with a raft of seconds and thirds. Then came Reims. Spence took over as Clark’s F1 team-mate at the British GP. It was perhaps 18 months too early, for he proved far more circumspect than his predecessor and didn’t score a world championship podium until his 15th start — third in Mexico ’65.

“Mike was neat and tidy, easy on the car,” says Team Lotus chief mechanic Jim Endruweit. “But it’s possible he was overawed. In some ways it didn’t matter who was our number two. We had two cars but it’s no surprise that Jimmy was the focus: his car had to be 110 per cent, the other could get by at 100. The mechanics would do anything for Jimmy. If the number two had kicked up he might not have got as much ‘service with a smile’.”

But Spence didn’t even kick up during his 1966 season with Reg Parnell Racing, a campaign stacked with retirements, leavened only by two fifths – Holland and Italy – in its Lotus-BRM 25. “There was no side to Mike,” says team manager Tim Parnell. “He just got on with it.” Matters looked a little rosier when Spence followed Parnell to the works BRM squad for 1967. Its H16 engine was a nightmare, but while Jackie Stewart, starburst career falling from the sky, was tearing his hair out, Spence kept his on and brought the P83 home in the points five times – four fifths and a sixth – which spoke volumes for his mechanical sympathy.

“Mike was a true gentleman,” says Stewart. “He was smooth and unspectacular, a solid performer who worked well with the engineers. But he never pushed himself forward for a drive and always seemed destined to be a very good number two.”

Stewart’s assessment is probably fair. But Spence’s sports car stint with Chaparral that season had allowed onlookers to glimpse a latent side to his talent. He joined Jim Hall’s team at Daytona, where he and Phil Hill led for three hours before the latter crashed. Co-driven by Hall, Spence also led at Sebring. This was a new experience: fastest car in the race, (joint) number one in the team. And he was in his element with the advanced 2F, adapting neatly to its two-pedal layout and driver-adjustable rear wing.

“Mike was a really good guy who had a lot of ability,” says Hall. “He gave us exactly what we needed: he was quick and didn’t damage the car. He was better than I expected. I thought he was confident, professional and comfortable with the car from the start. Phil was vocal about a few things he didn’t like about the car, but if Mike had any complaints, he didn’t make them to me.”

Spence and the 2F set fastest lap at Sebring, battled with the Ferrari P4s at Monza and set fastest lap at Spa too. Le Mans, though, was the main target for the now Frankfurt-based team. Beaten only by Mario Andretti’s Ford MkIV in practice, the Chaparral took the fight to FoMoCo until its recurring weakness, its transmission, wilted.

Some compensation came in the BOAC 500, final round of the World Championship, at Brands Hatch on July 30. Although outpaced by the Lola T70s of Denny Hulme and John Surtees in qualifying, the 2F packed 211 laps into six punishing hours to score a famous victory. It was an assured performance that brought Hill’s career to a glorious end – and looked to have kick-started Spence’s. Doors were opening and he was finally realising he had more to offer – in and out of the car. He was translating that ‘aloofness’ into self-effacing charm and his technical grasp into racy speed.

Pedro Rodríguez, his new BRM team-mate, was talented, but he was no Clark or Stewart. The number one slot was up for grabs and Spence knew he had to move up to the next level. Having pensioned off the H16 in South Africa, he quickly got to grips with its replacement, Len Terry’s V12 P126. “Mike was impressed with it immediately,” says Terry, “He reckoned the only thing it lacked was another 20 horsepower.”

Rodríguez returned to the UK in March, honed and sharp after driving a P126 during the Tasman Series. But the Mexican had no answer to a fired-up Spence at the Race of Champions; Mike started from the middle of the front row and was holding a secure second when an oil pipe wore through against the undulating track. At Silverstone’s International Trophy on April 25, after a poignant silence in Clark’s memory, Spence battled against the DFV-powered McLaren M7As of Bruce McLaren and Hulme, passing and repassing for the lead. This time he was halted by a broken timing chain albeit after 40 laps that had made everyone sit up. He was carving a new reputation.

That includes his exploits in the Ford F3L prototype, run by Alan Mann, at its debut race, the BOAC 500 on April 7 1968. “Before he drove for me I’d been dismissive of Mike,” admits Mann. “When it became clear that Clark and [Graham] Hill wouldn’t be available to us for Brands because they had a Hockenheim F2 race to do instead, Mike looked a safe bet. But he shook the life out of me. He was much more confident than I’d expected. He was quick and very good on the technical side. Frank Gardner and Jack Brabham had driven the F3L and not liked it; they just said it didn’t feel right, that maybe its wheelbase was too short. After four laps of Goodwood Mike came in and said he thought the rack was loose. He was right its mountings were flexing. He then asked for four or five inches more rear spoiler and promptly found another two seconds.”

When it became clear that only one F3L would be fit to start, Mann chose Spence (ahead of Hulme and Jochen Rindt) to partner McLaren. They led briefly before a rubber doughnut sheared.

That weekend, of course, was marred by Jim Clark’s death at Hockenheim. But racing goes on, and a bereaved Chapman asked Spence to take the Scot’s place at Indy. “Mike and I talked for an hour about it,” says Mann. “He had some bad thoughts about getting back in a Lotus but he knew it was a great opportunity. It was from my office that he called Colin to accept.”

Parnell: “Mike was a brilliant test driver. Chapman valued him highly in that respect. That’s why he asked him over.”

The deal, though, was open-ended: if everything went well in his first week at the Brickyard, Lotus would sign Spence for the 500 on the understanding he might be seconded to Andy Granatelli’s STP half of the operation.

Spence had only briefly sampled the four-wheel-drive turbine car at Silverstone, but he took to Indy as effortlessly as Clark had six years before. By Tuesday May 7, his final scheduled day, he was consistently at 169mph, despite gusting winds and full tanks. His best lap – a 169.555mph – was the second-fastest of all time. His speed, relaxed demeanour and good humour had won over the locals. Mike Spence had, at last, arrived in the Big Time.

But few can have enjoyed a briefer spell in the spotlight.

Lotus, delighted with the day, was ready to leave when Granatelli persuaded Chapman to put Spence in one of his cars. Reigning USAC sprint car champion Greg Weld, another rookie, was having problems dialling in to this unusual car. Spence being Spence, he was happy to give it a go. He was up to 163mph by his second lap.

Turn 1 is regarded as the trickiest of the four, especially when the grandstands cast their shadow late in the day. Was Spence deceived by a sudden change in light level, or was he ‘adjusting’ to a steward’s quiet word about running too low on his fast laps? Whatever, it was a small error with huge consequences. The bathtub monocoque absorbed the impact well. But the offside front wheel pivoted around the steering arm, the only item still attaching it to the chassis, and struck Spence on the head. It was a fatal blow.

But racing goes on, and at Monaco three weeks later Richard Attwood replaced Spence at BRM and finished second, just 2.2sec behind Hill’s Lotus. “Richard did a great job, but I genuinely think Mike could have won that day,” says Terry. Four days after Monaco, Joe Leonard, Spence’s replacement in 56/1, started Indy from pole and was within nine laps of victory when its fuel-pump shaft sheared. Might smooth, sensitive Spence have won that day too?

“Mike was maturing into a very accomplished driver,” says John Blunsden, then GP correspondent of The Times. “He was revealing a quality we perhaps hadn’t realised he had. The real shame of it was that it was such an unnecessary accident, in that he was doing the decent thing, helping out another driver.”

Parnell concludes: “That was typical of Mike. He was the nicest bloke I ever met in motor racing.”

Too nice, as it turned out.