Despite impressing on his maiden F1 outings with Williams and McLaren, none of the sport's leading teams were prepared to take a chance of signing the rookie for a full season in 1984.
Senna was already a double Formula Ford champion at that point and, at the time of his first-ever F1 run with Frank Williams equipe
at Donington Park, was in the midst of an F3 campaign that would also result in the title, albeit after a frenetic battle with Martin Brundle. However, despite posting Williams' best-ever time around the Donington circuit, and then going on to impress in the McLaren at Silverstone - when he beat Niki Lauda's British GP qualifying time while sharing track time with Brundle and the late Stefan Bellof - Senna would wind up making the jump to F1 with the relatively lowly Toleman team [check out remarkable video footage of those tests - click here
It was something of a chance meeting aboard a flight bound for the Zandvoort Euro FF2000 round in 1982 that launched Senna's run with Williams, and the Brazilian apparently pestered the eponymous team owner for months before finally being given his chance. Having been impressed with what he saw of the Brazilian in Holland and thereafter, however, Williams offered Senna a chance to drive the Monaco-winning FW08C at Donington midway through the following year.
Williams would reveal that conditions in the cockpit were far from ideal for the youngster, who had to shoe-horn himself into regular pilot Jacques Laffite's seat, and confirmed that he ran on the 'B' compound Goodyear tyres in use at the time. There were no incidents of note during the test - indeed Williams noted that Senna rode the kerbs just once in 83 laps - as the Brazilian gave an account of himself good enough to awaken interest elsewhere.
McLaren didn't have to be impressed to include Senna in a small group test at Silverstone in late October, for the Brazilian was invited, along with Brundle, to take part after finishing in the top two in the British F3 standings. Bellof was also present, ostensibly because he was among the favourites to join the Woking outfit in place of John Watson the following season.
On that occasion, Senna was benched after trying to go too fast too soon but, once allowed back into the Cosworth-powered MP4Cs, was quickly down to competitive lap times, eventually recording the fastest lap of the day at 1min 13.9s. Again, he complained of not being comfortable in the cockpit, and reckoned that he could operate the throttle as well as he would have liked, but he had done enough to impress team boss Ron Dennis, who noted that Senna's effort was particularly noteworthy given the cool autumnal conditions.
With Alain Prost already signed to drive alongside Lauda in 1984, McLaren was not an option for Senna if he was to make his grand prix debut the following year, and Williams, too, was off limits, given that 1982 world champion Keke Rosberg was to return alongside Laffite. Indeed, even though the Finn was being linked elsewhere at the time of Senna's test, Williams admitted that it would have preferred an experienced F1 pedaller over the F3 champion, especially as it, like McLaren, was in the process of joining the turbo-charged brigade.
The Brazilian was also linked to Brabham, which would go on to win the 1983 F1 title with Nelson Piquet, but could not strike a deal with Bernie Ecclestone - and would likely have been vetoed by his countryman if he had! Instead, despite Dennis apparently offering a funded season in F2 in exchange for first option on his services in future, Senna ultimately wound up at the tiny Toleman team which, being an emerging midfielder at the time, felt it could take a chance on the youngster even though it was already turbo-powered.
Senna tested with Toleman at Silverstone towards the end of the year, gradually acclimatising to the Hart engine in damp conditions, but still beating erstwhile team leader Derek Warwick's best mark. Turning up the wick in a drier afternoon session, he eventually recorded a 1min 11.0secs best, which would have registered among the top five race laps in the grand prix..... At that point, Toleman's future was in doubt without a tyre contract, but Pirelli stepped in and therefore played a major part in launching the Senna fable.
Partnered by former motorcycle champion, Senna was able to make a strong impression in the 1984 season, notably chasing Prost's McLaren to the line in a soaking wet Monaco GP. His performances naturally attracted attention and, when Lotus came calling, the Brazilian was prepared to jump ship for 1985, midway through a two-year deal with Toleman.
From there, his career became the stuff of legend, from his first F1 win with Lotus - in torrential conditions at Estoril - to the move to McLaren that eventually yielded three world titles. Eventually, Senna's top flight career came full circle, with a fateful return to Williams ten years after his F1 career began in earnest. The man who gave him his first test would later admit that not signing the Brazilian at the time was one of the biggest mistakes he had ever made....