The 'wrong tree' car that ignited the McLaren-Mercedes partnership

In 2021, McLaren will rekindle its relationship with Mercedes after a six-year intermission, following three disastrous years with Honda before an upturn in fortunes with Renault - which resulted in fourth in last year's constructors' championship.

But the team's decision to cast away from Renault next year will bring it into a second stint of the famous McLaren-Mercedes partnership - one which lasted 20 seasons in Formula 1 and yielded its most recent taste of championship-winning success back in 2008.

A quarter of a century ago, McLaren had endured a couple of lean years having ruled the late 1980s and the first part of the '90s with an iron fist. But its grip on the championship was prised apart by the technological prowess of Williams, while Honda departed from F1 at the end of 1992 after McLaren had failed to win a title for the first time since 1987.

Having been forced to take a supply of customer Fords for 1993, with the stipulation that they would remain a few steps behind the works Benetton team, McLaren still managed to win five races despite a large deficit to the Williams-Renaults in the power stakes.

Although it had looked set to switch to a works Lamborghini deal, McLaren then decided to join forces with Peugeot for 1994, but their alliance lasted only one year thanks to an engine that would frequently like to spontaneously combust. Having already had enough with the sudden deluge of politicking brought on by Peugeot's involvement (and, presumably, the company's insistence of foisting Philippe Alliot upon it as a replacement for the banned Mika Hakkinen at the Hungaroring), McLaren swooped for Mercedes.

A long-time partner of the Sauber squad in its endurance racing days, Mercedes had entered F1 with the Swiss outfit in 1993, but linked up with McLaren for '95 as Peter Sauber's team took the lead Ford contract ditched by Benetton in favour of Renault power.

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The Mercedes engines were produced by Ilmor, which at last had a household name to align itself with after its low-key entrance into F1 with Sauber.

After a troubled 1994, McLaren had also bolstered its '95 cast with another big-name signing; replacing Martin Brundle was Nigel Mansell, embarking on what was intended to be a first full season in F1 since his 1992 championship-winning campaign after title sponsor Marlboro asked for a world champion driver. Alongside the 1993 Indycar champion, Hakkinen was retained having managed fourth in the 1994 drivers' championship stakes, despite the Peugeot's shortcomings.

The 1995 car, the MP4/10, was certainly distinctive. McLaren made the decision to raise the nose to improve the flow to the car's underside, which ended in a sharp point. Doing so aimed to negate the loss of downforce enacted by the swathe of new technical regulations, which mandated a stepped floor and an increased ride height to reduce the speeds of the car - a legacy of Ayrton Senna's fatal accident at Imola the previous year. There was also an engine capacity change - from 3.5 litres down to three - to further inhibit the amount of power.

Having also had to make an entirely new chassis to meet F1's new safety requirements, it became apparent early on that Mansell couldn't fit in the car. Therefore, McLaren's resources were spent on building a car that could fit his frame, meaning that test driver Mark Blundell had to deputise for his compatriot in the opening two rounds.

"We were all looking for downforce and not necessarily efficiency. So that's why I call it barking up the wrong tree" Henri Durand

Aerodynamically, the MP4/10 had some innovations; the central wing attached to the rear of the engine cover was, in many ways, a precursor to the T-wing-and-shark-fin combination seen throughout the 2017 season. But there was an imbalance between the aero output and the overall efficiency of the car - which meant that McLaren was still firmly some way off from Benetton, Williams and Ferrari.

"We just barked up the wrong tree," recalls Henri Durand, who was then McLaren's head of aerodynamics. "And I bear some responsibility on that. I accept that. We had a very different set of regulations to work on; it was a pretty disturbed '94 obviously with Ayrton's accident, which emotionally affected a lot of people. In hindsight, we probably should have started the project earlier.

"The Mercedes was a great engine; Mario [Illien] and the team did a wonderful job. Because the regulation change was so drastic, we had lost so much downforce; we were all looking for downforce and not necessarily efficiency. So that's why I call it barking up the wrong tree.

"There was a little bit of innovation on it; we were the first ones to effectively use the central diffuser by sucking on the side, which Williams copied, but did a much better execution of it, but they changed the gearbox to do that when they did their evolution in the middle of the season."

Hakkinen plonked the new McLaren seventh on the grid for the Brazil season opener, two spots ahead of Blundell as the pair was separated, ironically, by the Peugeot-powered Jordan of Eddie Irvine.

The duo finished fourth and sixth, although Hakkinen was briefly promoted to second after winner Michael Schumacher's Benetton and runner-up David Coulthard's Williams were excluded from the race results for fuel irregularities. On appeal, their results were reinstated - much to the apoplexy of fleeting victor Gerhard Berger, but from McLaren's standpoint it was an encouraging start to life with the Mercedes engines.

The follow-up round in Argentina was less auspicious and, although Hakkinen had darted into third from fifth on the grid, a first-lap pile-up instigated by a spinning Jean Alesi forced a restart. Hakkinen then clipped Irvine into the first corner on the second start, going out on the spot - as Blundell later succumbed to an oil leak.

Mansell was finally back in the saddle for his long-awaited first race with McLaren for the San Marino Grand Prix at Imola, at which the team could make a change to boost the mid-wing. Another legacy of the 1994 season was the slot in the airbox, which was to restrict the amount of airflow entering the engine intake to reduce the overall power. That ruling was eventually rolled back on, as the reduction in engine capacity had proven to be enough, which McLaren was not anticipating to get the most out of its engine cover design.

Durand, who would later have a stint as technical director with the doomed Prost team, before joining Jordan and then moving to the US and landing at Toyota Racing Development in NASCAR, duly takes up the story.

"Our solution with the midship wing and then the engine cover," he recalls, "originally had the venting, which was on the pressure zone. The midship wing on paper would have been a bit of an advantage. Once that regulation was cancelled after two-three races, that had gone, and the midship wing provided a bit more downforce but it was not necessarily very efficient.

"It was providing more downforce in a straight line, but in yaw it was not substantial and we understood that only after a while, because at the time we were not looking too much at yaw and steer. Part of its downforce had gone. So I would say, I can raise my hand and say 'guilty', but you have to say also that this was before the time when the aero groups became a very large group of people."

The team eventually ditched the mid-wing partway through the season, as the downforce it offered wasn't worth the drag penalty it caused - and also reverted to a more conventional engine cover.

For his return at Imola, Mansell qualified a respectable ninth while Hakkinen was sixth despite failing to set a second-qualifying session time. Mansell, after a poor start in which he fell down to 14th, spent a lengthy portion of the race running among the points-paying positions, but a late clash with Irvine shuffled him back down to 10th as Hakkinen rescued a fifth-place finish.

Mansell's McLaren career lasted just one more round in Spain; having complained about the MP4/10's handling characteristics all weekend, he called it a day after just 18 laps having had enough - walking out on the team immediately afterwards.

Blundell was recalled after that, and was arguably a more consistent presence in the points than Hakkinen, who instead picked up the big-ticket results in the form of two second-place finishes as mechanical and electrical problems precluded him from capitalising on strong qualifying results. His runner-up finish at Monza underlined the potential of the Mercedes powerplant, but the Finn's season was briefly interrupted by appendicitis - meaning 1994 British Formula 3 champion Jan Magnussen was called upon to cover Hakkinen at Aida.

"We had Magic Mika, a great race team which managed to squeeze every bit of juice out of this fruit and effectively got some very respectable results, so I put it on Mika's talents and the race team's talent" Henri Durand

On his return, the Finn was in resurgent form at Suzuka, bagging third on the grid and claiming second at the finish - just 20 seconds down on winner Schumacher. But hopes of finishing the season with a flourish were plunged into an altogether sombre weekend at Adelaide; Hakkinen suffered a puncture in the first qualifying session and crashed heavily, resulting in a fractured skull and a trapped airway.

An emergency tracheotomy at the side of the circuit saved Hakkinen's life, as McLaren was forced to contest the Australian Grand Prix with just Blundell in the running.

In a race dominated by Damon Hill, who routed the field with a two-lap buffer to second-placed Olivier Panis, Blundell rescued fourth to bring the MP4/10's service to an end. It would be his final F1 outing before heading Stateside, where he managed three wins in five seasons for PacWest Racing, all coming in 1997.

Although McLaren's start to life with Mercedes had been difficult, perhaps the phrase "under pressure, diamonds are formed" had proved true, and later in the decade McLaren and Mercedes won two titles with Hakkinen.

"You know, we were not necessarily as reactive as we should've been," Durand admits. "So when you go on the wrong path, it's very difficult to recover. Williams managed to do the diffuser with new gearbox in the middle of the season, and that proved that they were more reactive than we were.

"On the other side, we had Magic Mika, a great race team which managed to squeeze every bit of juice out of this fruit and effectively got some very respectable results, so I put it on Mika's talents and the race team's talent."

But the MP4/10, despite its flaws, laid the groundwork for a highly productive partnership. As McLaren begins its new chapter with Mercedes in 2021, it shouldn't be disheartened by any troubled starts - indeed, it has precedent. From little acorns, big trees grow.