After weeks of protracted deliberations over their driver line-up for next season, McLaren finally ended the saga on Thursday morning by announcing Button will be staying in a race seat at the expense of 2014 team-mate Kevin Magnussen. The Dane has, however, been retained as McLaren's new test and reserve driver.

"Fernando and Jenson have started a combined total of precisely 500 grands prix between them – a mighty aggregate – and have won 47 of them," declared team boss Ron Dennis. “I can safely say, therefore, that we now have by an order of magnitude the best driver line-up of any current Formula 1 team."

While Mercedes might quibble with that assessment, the Alonso and Button partnership – a vivid contrast in character and driving styles – is a mouthwatering prospect. 

Following his split with Ferrari, Alonso returns to McLaren seven years after an ill-fated single campaign when his relationship with Dennis disintegrated and the team became embroiled in the ignominious and infamous Spygate scandal. Little wonder then that McLaren hashtagged their announcement as #FriendsReunited. 

“I am joining this project with enormous enthusiasm and determination, knowing that it may require some time to achieve the results we are aiming for, which is no problem for me," said Alonso. "I will do everything in my power to deliver for everyone and for our team, based on a formula that has always worked for me: effort, sacrifice, perseverance and faith.

“We have time, we have hopes and we have the necessary resources. Let the legend return: that is our challenge.”

Confirmation that Button will stay on for a sixth season at McLaren and a 16th year in F1 is sure to delight the 2009 world champion’s legion of fans who for weeks have been campaigning on social media for the Briton to be handed a contract renewal.

At 33 and 34 years of age respectively, Alonso and Button will form by far the oldest partnership on the grid in 2015. 

Such experience is likely to prove invaluable in the first year of McLaren’s reunion with engine suppliers Honda as the team plot a return to the front. But the veteran status of both Alonso and Button also means that Magnussen's absence from the grid may prove shortlived, although Dennis has revealed that both drivers have signed multi-year deals. 

“We have both agreed that more than one year is a must,” said the Englishman. “This is a new project and an exciting project. To be part of the legendary partnership between McLaren and Honda is not a one-year thing.

While Alonso is understood to have put pen to paper several months ago, Button's retention was only rubber-stamped on Wednesday night after the 2009 title winner agreed to take a substantial pay-cut. 

“Like Fernando, I am certain that McLaren and Honda will achieve great things together, and I feel sure that, working together, all of us will pull incredibly hard to create a brilliantly effective winning team," added Button. "I am very much looking forward to having a driver as fast and as experienced as Fernando as my team-mate. I am sure we will work extremely well together.”

While the Alonso element of McLaren’s 2015 line-up has been an open secret in F1 for weeks, the re-signing of the two-times champion is undoubtedly a significant coup for an outfit which last won a race in 2012 and has claimed only one world title this century.

The Spaniard’s signing, seven years after the Spygate scandal resulted in the team being fined $100m and Alonso being turfed out less than a year after joining the Woking outfit, constitutes a remarkable remarriage. As the team imploded, allowing Ferrari’s Kimi Raikkonen to snatch the 2007 title by a point from Alonso and a then rookie Lewis Hamilton, the Spaniard’s relationship with boss Dennis disintegrated to such an extent that the year ended with the pair no longer on speaking terms. “It is not a secret that I never really felt at home,” Alonso admitted upon his departure.

Yet half a decade of frustration can make for some surprising about-turns. Tired of out-performing inadequate machinery at Ferrari, Alonso informed the Scuderia hierarchy he had lost faith with the team this summer, paving the way for a previously-unthinkable return to McLaren at the start of their new Honda era.

"I have never hidden my deep admiration for Ayrton Senna, my favourite driver, my idol on track, my reference," he explained.

“I still remember, as a kid, the posters in my wardrobe, my toy cars in which I dreamed I would one day emulate Ayrton, and the kart that my father built for my older sister, and that I ended up falling in love with. That kart had the livery of one of the most legendary partnerships in the history of Formula 1, McLaren-Honda, the car that Ayrton drove, the same partnership to which I am now honoured to join, to take part in the next Formula 1 world championship."

It's a delicious fact that whereas Alonso cited Senna's influence in his decision to return to McLaren-Honda, Button revealed "it was the exploits of his McLaren-Honda team-mate Alain Prost that inspired me most as a boy" in the press release announcing their union. Even if Button-Alonso produces half as many fireworks as their fabled predecessors, 2015 should be spectacular.

“I am joining this project with enormous enthusiasm and determination, knowing that it may require some time to achieve the results we are aiming for, which is no problem for me," continued Alonso.

“Over the past year I have received several offers, some of them really tempting, given the current performance of some of the teams that showed interest. But, more than a year ago, McLaren-Honda contacted me and asked me to take part, in a very active way, in the return of their partnership – a partnership that dominated the Formula 1 scene for so long."

Whether it can dominate F1 again remains to be seen.