Following in the fine tradition of Sir Winston Churchill

Anyone can rat, but it takes a certain ingenuity to re-rat.

is attributed to Churchill, commenting about his leaving the Liberals to rejoin the Conservatives.

Of course, the Tory MP Quentin Davies has merely 'ratted' today, but with impeccable timing. Tomorrow Gordon Brown will take over from Blair, and on Thursday the new cabinet will be named. As Davies has once worked on Northern Ireland, I daresay that there will be speculation that he's after the job that Paddy Ashdown turned down last week.

Davies has issued an open letter to David Cameron, outlining the reasons for his defection:

Under your leadership the Conservative party appears to me to have ceased collectively to believe in anything, or to stand for anything.

It has no bedrock. It exists on shifting sands. A sense of mission has been replaced by a PR agenda.

Hmm.

You had come to office as leader of the party committed to break a solemn agreement we had with the European People's party to sit with them in the EPP-ED Group during the currency of this European parliament.

For seven months you vacillated, and during that time we had several conversations.

It was quite clear to me that you had no qualms in principle about tearing up this agreement, and that it was only the balance of prevailing political pressures which led you ultimately to stop short of doing so (though since then you have hardly acted in good faith in continuing with the agreement, for example you never attend the EPP-ED Summits claiming that you are "too busy" - even though half a dozen or more prime ministers are always present.)

This is crucial. When Cameron argued for a referendum on the new EU Treaty / reheated Constitution in Parliament yesterday, it was pointed out by Blair that the EPP-ED had met last week to consider the treaty, along with senior right wing Europeans. If it's so important that a referendum is required, what was Cameron doing last week that stopped him engaging himself in the process?

You are the first leader of the Conservative party who (for different reasons) will not be received either by the president of the United States, or by the chancellor of Germany (up to, and very much including, Iain Duncan Smith every one of your predecessors was most welcome both in the White House and in all the chancelleries of Europe).

It is fair to say that you have so far made a shambles of your foreign policy, and that would be a great handicap to you - and, more seriously, to the country - if you ever came to power.

Ouch!

Although you have many positive qualities you have three, superficiality, unreliability and an apparent lack of any clear convictions, which in my view ought to exclude you from the position of national leadership to which you aspire and which it is the presumed purpose of the Conservative party to achieve.

Double Ouch!

To put the icing on the cake, as far as those of us who may be less than sympathetic to the fortunes of the Tories, Quentin Davies is the MP for Grantham and Stamford, the birthplace of Maggie Thatcher.