At what point did Cameron and Clegg jump into bed?

We may never know, but an early deal would explain much about the coalition.

Some of the details about the talks between the party leaders in preparation for the aftermath of election 2010 may remain secret for decades under Whitehall's "30-year rule". But it is becoming increasingly clear that the Liberal Democrats with Nick Clegg at their helm were pretty determined, early on in the negotiations, to get into bed with the Tories.

I was among those who argued that Clegg may have made a tactical error during the campaign by: a) going well out of his way to distance himself from Gordon Brown and b) ushering in the concept of working with the party with apparently the biggest "mandate" after the election.

In fact, it is now clear that Clegg did not, in his own terms, make an "error". Rather, his position was in line with the one he later took: forming a government with the Conservatives.

The question now is, at what point did he take that decision?, and for what reasons? I am not the first to point out that the Lib Dem-Tory message on the Friday after election night appeared swift and indeed co-ordinated. Some MPs are now wondering whether they had contact about the coalition before the election, and if so what form that took.

The answers are not yet clear, but I'm working on an investigation for later this week, and it's looking at the moment like the Liberal Democrat leadership may have been "dishonest" about its reasons for siding with the Tories, and fundamentally unserious about an alliance with Labour; more so than the other way around.

Whether the Lib Dems have been led into a "honeytrap" by the Tories remains to be seen.

James Macintyre is political correspondent for the New Statesman.