Lord Pearson is a man of principle and a passionate foe of the EU superstate. His defection to UKIP while hardly a surprise – he had already lost the Tory whip for advocating voting for UKIP – would be hard to spin as the act of a madman. His contention is that he is acting in the national, not party, interest and that he remains a conservative.

Guido is told that he exacted a promise from Nigel Farage as a condition of joining. UKIP, Pearson was promised, would not field candidates against Eurosceptic Tory candidates. Pearson does not believe that defeating friendly anti-EU allies would serve the national interest. In 2005 UKIP were reckoned to have cost the Tories six seats, including in Thanet South where the candidate was an ardent anti-EU campaigner.

This commitment could in some ways secure Cameron’s right-wing flank and benefit UKIP by allowing them to focus resources on more useful targets. It will also encourage Eurosceptics in the Conservative party to advertise their loyalties and put pressure on the Europhiles. The old UKIP policy scared many wavering Conservative voters who feared voting UKIP would only benefit Labour and the LibDems. Lord Pearson may yet have done the Conservative party a final great service…