The Sun newspaper’s decision to back the Conservatives after supporting New Labour for 12 years is a blow to Gordon Brown’s chances but only marginally. It is also a curiously Old Media gesture from a title that has shown some skill at adapting to the new media environment.

It reminds us that many years ago, before Tony Blair and the blogosphere, a newspaper like The Sun could claim to have swung a tight election.

Of course, my academic colleagues will point out that voters make their minds up on a range of factors. They would characterise the role of newspapers as ‘framing’ the debate rather than changing people’s political preferences directly.

In that sense Murdoch is running way behind public opinion which long ago lost faith in Brown and Labour. But this gesture will add to the sense that support is draining away, so it’s not helpful to Number 10.

This kind of editorial position-taking is terribily important within newsrooms and it is also part of the ritual that makes up the curious relationship that British newspapers with their readers. It will be fun to see if the struggling Independent seeks some publicity by going for a surprise choice (which in this case could be Labour or the Tories).

Will the reprieved Observer follow the Guardian and back Labour or will its ‘liberal’ impulse swing it to Nick Clegg? As for the rest it is fairly predictable. The Sun is the swing voter in newspaper terms which is partly why it’s seen as significant. It has as many of the critical AB1 readers as many of the broadsheets. It also matters because the implication is that when Rupert gives you his backing, you then owe his corporate interests something in return.

Of course, some knee-jerk leftists are delighted that they can resume hostilities with the ogre from Oz, while others point out that there is little evidence it will have any impact. There is even some slightly wishful thinking that it might backfire.