Buckingham MP John Bercow has only been in the House of Commons for seven years, but already he appears to have settled into the role Michael Heseltine, Ken Clarke and others fit so well: a Tory grandee, normally of advanced years, who gets headlines only by attacking his own side - and who does so regularly.
There has even been some speculation in recent months on whether Bercow will at some point defect to Labour. A man who started out in politics as Chairman of the Monday Club's Race and Repatriation Committee, and who risked the chance of a seat in Parliament through vigorous campaigning against Maastricht, he became a classic 'moderniser' in 2001 and has since moved still further left - matching social liberalism to a social democratic stance on the state. Since he left Iain Duncan Smith's Shadow Cabinet in 2002, he has matched his preoccupation with gay issues to a dismissal of tax cuts, demanding instead higher government spending on the poor, home and abroad. His famed euroscepticism was perhaps the last reason for him to belong to the Conservative Party.
In an interview with the Independent this month, he appears to have rushed another few feet still further down the path that seems to lead to his joining Labour. He expressed clear support for Blair and Milburn when it comes to public services - the very issue he was strongly urging fringe meetings at the Tory Party Conference just two years ago to use as a stick with which to beat Labour. In slamming the Daily Mail's "contrived hysteria", he echoed Polly Toynbee's attacks on the Tory press perfectly. Asked if Michael Howard was in danger of looking opportunistic, Bercow went even further than his interrogator in attacking his leader. On foreign affairs, however, he was willing to criticise the government: Blair isn't being Blairite enough! Even on Europe, he showed himself backtracking. He was damning in attacking Tory "europhobia" in the 2001 General Election campaign - a time when the Conservative Party was less eurosceptic than it is now.
The end of the interview left little room for doubt:

Some senior Conservatives fear Mr Bercow will defect to the Labour Party. Mr Bercow will make no public comment about that. Instead he insists: "I am working for a modern, progressive Conservative Party."

He left our interview to speak in north London on behalf of a Tory candidate. For now, John Bercow is an active and diligent Conservative. He will remain one if the party moves "very quickly" to what he defines as the progressive centre ground. [Emphasis mine]

The Telegraph reports:

One Tory frontbencher said: "It is extraordinary to give an interview like this. There can only be one possible explanation: he's getting ready to defect."

Bercow issued a brief denial when the conclusion to the interview received enough attention, but in the face of so much contrary evidence, I suspect few minds will be set at ease.
So what if he does defect? It may be that he will deliberately make the jump at the worst possible moment for the Tories as an election approaches. But even then, the important point is not to overreact. There is nothing inherently dishonourable about changing one's mind, even as dramatically as this. The honour Bercow shows towards his constituents and party workers remains to be seen, but he does have a right to leave the Tory Party if he feels another political force will better suit him.
My own view is that the leading 'modernisers' in general have a somewhat flawed understanding of real politics, which elevates peripheral issues to the centre stage in the belief that significant numbers of votes hinge on implementing all-women shortlists and the like. Bercow is not the only 'moderniser' to have emerged from a hard-right that paid scarcely any heed to the electoral needs of the real world. Coming from that perspective and later discovering the need to win over millions, it is easy to see why such people would start conceding principles, but then not know quite when it is prudent to stop. Those who had been pragmatists all along would not have to make such an adjustment because realism has always been a clear part of their more mainstream conservatism. One can see a similar pattern in the recent history of the Labour Party, as the pragmatists of the Old Labour Right were surpassed by colleagues even more to the right, but who started out in the Kinnockite soft Left, and having begun to give up their principles, have still not found a convenient moment to stop.
Unlike Labour, the Conservative Party is not likely to change along with the views of its self-styled 'modernisers' - and nor does it need to. If John Bercow and a few others will not accept that, Conservatives can hope any defections will be graceful, and can ensure they are not seriously damaging by suppressing their own anger and mustering their own grace, ensuring the story generates as little coverage as possible.