JENSON BUTTON has "no reason not to get the job done" after converting the sceptics to secure a new two-year contract at McLaren, according to Ron Dennis.

Chief executive Dennis claimed "the two-year contract was my idea, not Jenson's" after the 34-year-old Briton was confirmed alongside Fernando Alonso at McLaren for next season.

Dennis offered "no apologies" for delaying confirming McLaren's team line-up for more than a month, revealing the onus had been on Button to convince team bosses he was fully committed to the challenge.

The McLaren CEO also conceded though that FIA contractual obligations to retain three drivers in part led to the decision to hand Button his 16th year in Formula One, with Kevin Magnussen retained as test driver.

"He has no reason now not to get the job done, no reason," said Dennis, demanding Button now delivers.

"I make no apologies for having the level of consideration that I gave ultimately to the decision.

"The reality is that in any negotiation you arrive at the point where you're addressing concerns.

"And when we were discussing internally we came up with a series of things that gave people cause for concern.

"When I discussed these with Jenson, the level of transparency would be hard to believe, but that's only possible when you're dealing with the sort of maturity and understanding that you have with experienced racing drivers.

"I spent the weekend thinking about solutions as opposed to problems.

"I gave Jenson some ideas on solutions, and he just said 'no problem', and that was it.

"Then it was very easy.

"Then everybody who had been slightly this way or that way aligned, and we had the very thing, consensus.

"You want people to agree with your decisions in order that everybody takes responsibility for the outcome.

"We've been in deep debate about it, and there was a turning point for me strangely, a conversation that took place between Jenson and me after the race.

"It was in contrast to the previous month, and re-energised my belief that Jenson really wants to be in a Formula One car, and that he can kick Fernando's butt."

Dennis claimed he had faced a "painful decision" to choose between 34-year-old stalwart Button and 22-year-old rookie Magnussen to partner Spaniard Alonso in the revamped McLaren Honda team.

The McLaren boss vowed in September to have the decision made by November, but then delayed his call by more than a month, with Button lobbying successfully for a stay of execution.

"We now have a contractual obligation to run three cars in the event that the grid falls below 16 cars or less," said Dennis.

"I still feel two teams have great challenges left to get to next year's grid.

"And it is my intention to try to assist them to that, because I believe that third cars are not good for F1.

"However we have a contract: and if we have to run those three cars I want to have the best drivers.

"Hence the decision was a little bit influenced by that likelihood.

"While it was a little painful for the two drivers, the pain for them would have been nothing compared to the pain for me if my decision was wrong."

A visibly-delighted Button vowed to remain at McLaren "for the long-term", before refusing to expand on a worrying two months that almost saw him forced out of F1 entirely.

"More than one year is a must," said Button.

"This is not just a one-year thing.

"I'm very much looking forward to more than one year.

"I'm not just here to be around for one year.

"I'm hopefully here for the long-term.

"I've been very open in how I've felt, I don't think there's any reason to comment any further.

"The positive is where we are right now, and we move forward from here."