Jenson Button will be handed a remarkable reprieve when he is named on Thursday as a McLaren race driver for 2015.

The 34-year-old Briton had given up all hope of taking his Formula One career into a 16th season as McLaren bosses wanted to plump for their Danish rookie Kevin Magnussen to partner the incoming Fernando Alonso.

But that decision was never rubber-stamped, and weeks of uncertainty began.

2009 world champion Jenson Button has been retained by McLaren for the 2015 season

Two-time world champion Fernando Alonso will re-join McLaren from Ferrari having left in 2007

Kevin Magnussen faces uncertain future after missing out on McLaren seat in 2015

Now Sportsmail has learned from an impeccably-placed source within McLaren that Button has been offered a new contract and will be unveiled, along with Alonso, at McLaren’s base in Woking.

Button’s good news means that McLaren’s new partnership with Honda will start in dazzling style: with two drivers who have three world titles between them.

Whether Magnussen will be kept on, in one form or another, remains to be seen.

It seems likely that the move to keep Button came about after McLaren chairman Ron Dennis took into account the wishes of his shareholders and Honda, who established a good relationship with Button when he drove for them from 2003 to 2008.

Button took to Twitter to reveal his happiness at staying on with McLaren for the 2015 season

The 34-year-old also welcomed new team-mate Fernando Alonso to McLaren following his switch from Ferrari

In a succession of tweets Button showed his support for Magnussen - stating he'll be back racing in the sport

For a long time Dennis had shown no inclination to re-sign Button. Indeed, both he and racing director Eric Boullier privately indicated that they favoured the blend of experience and youth offered by Magnussen, 22, and Alonso, 33. That Button outscored Magnussen 126 points to 55 last season seemed not to be enough.

Button grew so frustrated with his treatment that before the penultimate race in Brazil he wondered aloud if he would even accept a new contract if one was forthcoming. ‘That’s a good question,’ he said. He also drew up plans to take part in the World Endurance Championship.

But the pendulum gradually swung his way as a series of deadlines were missed.

First, McLaren said their driver line-up would be announced before the season-closing Abu Dhabi Grand Prix. They then deferred it until no earlier than December 1.

Button won the world title with Brawn back in 2009 and has been at McLaren since 2010

Dennis’s slow deliberations frustrated a number of his staff, as well as fans who complained on the internet. Even when he discussed the team’s driver line-up at a board meeting last week, there was still no decision.

A power struggle at the top between Dennis and his fellow shareholder Mansour Ojjeh, the Saudi Arabian entrepreneur, may have been one reason for the impasse.

Button said all along that he did not want to stay for the sake of money. He is already ranked Britain’s second-richest sportsman behind Lewis Hamilton in the Sunday Times Rich List with £63m.