D Day for Button and Magnussen as white smoke rises from McLaren

Tomorrow morning at McLaren headquarters the team will announce its driver line up for 2015, with plenty of speculation on both sides; either Jenson Button or Kevin Magnussen will get the nod, but which one?

The background to this story is long and drawn out; it revolves around Ron Dennis' return to the helm at McLaren, replacing Martin Whitmarsh, a year ago.

The deal was that Dennis was to find investment to buy out other shareholders and secure a title sponsor by the end of the season; but having failed to do that in time, he extended the deadline into January.

The team focussed on securing the signature of Fernando Alonso, once it was clear that he and Ferrari were separating and from there the decision on whether to partner him with Button or Magnussen has been tied up with the shareholders' dispute.

Dennis believed that his best chance of securing the finance was Magnussen's Danish backers, while the other shareholders feel that the team's best interests - and those of the sponsors - are best served by retaining Button, who is very popular with McLaren's sponsors and is a world champion. He also has strong ties with Honda, having raced for them in the late 2000s.

The sudden notification of tomorrow's driver announcement either indicates that the Danish money has come through, in which case it is Magnussen. Or that it hasn't and the other shareholders will get Button.

No-one connected with either side is willing to make any comment ahead of tomorrow's announcement. Danish media have been invited to attend the press conference, but that does not rule out the possibility that Magnussen will be announced as reserve driver for 2015. Button, 35 next month, is unlikely to go on for ever, after all.

The drawn out saga regarding Button and Magnussen has served to distract attention away from the Alonso aspect of this story. It is a hugely significant development for Alonso to return to the team with which he fell out so spectacularly in 2007. Both of their fortunes are saddled to each other and to Honda now.

Alonso's arrival is believed to bring with it interest from Spanish sponsors, with telecoms giant Movistar close to a deal. The brand is linked with O2 in the UK, a rival of McLaren's former sponsors Vodafone, which is believed to be regretting its decision to get out of F1, now that content is so clearly becoming the key to competitiveness in the future of mobile telephony.