I have a piece in this week's Jewish Chronicle on the likely change in British policy towards Israel. Here it is:

Both Israel and the US are about to get new leaders. So it would seem a tad unfair for us to be stuck with Gordon Brown for much longer. But with the latest poll showing a 28-point Conservative lead and Labour on course to lose the Glenrothes by-election, the removal vans may well soon be drawing up at Number 10. So the question is: how will the new brooms affect British policy towards Israel?

What is certainly clear is that no British prime minister is going to be as good a friend to Israel as Tony Blair. Remember: it wasn't Iraq that finally forced him out of office. It was the Second Lebanon War. Almost alone in the world, Blair refused to criticise Israel and championed its right to defend itself from terror. As the war dragged on, even the Americans started to condemn Israel's supposedly "disproportionate" response to Hizbollah. But Blair stood firm in support. And it was this, in the summer of 2006, which finally did for him, as Labour backbenchers plotted to remove him and many in the Cabinet made known their opposition to his stance.

This matters not just for historical interest but because it shows how any future Labour leader is likely to behave. Labour Friends of Israel may hold one of the best-attended receptions at the party conference, and it does a superb job at putting Israel's case within the party. But the tide long ago turned within the broad mass of the Labour Party away from its once instinctive sympathy towards Israel. The reasons for that are complex but run parallel to the spread of anti-Americanism and the Western self-loathing of so many on the left. Whatever the cause, the default position within the Parliamentary Labour Party, let alone the Labour Party at large, is now to view Israel as the main obstacle to peace.

Unlike Blair or Brown, the next Labour leader will be elected from a position of weakness. Blair could afford to ignore the rest of his party as he brought three landslide election victories. Brown, as the yearned-for hero over the sea, could initially have told his party that little green fairies were the answer to the Middle East's problems and been hailed as a sage; and he makes repeated references to his family and emotional ties to Israel. But the revelation that he was all hype and no substance has added political impotence to his incompetence.

Whatever the exact circumstances of Brown's departure, the next leader will be brought in to mitigate a disaster. He or she will have to work with, not in spite of, the party. And that means that the approach to Israel will be different, even through the filter of diplomatic language. Government policy will not do a volte face, but there will be much less reluctance to criticise Israeli policy and a greater readiness to imply that it is Israel which is the real block to peace. The priority for the next Labour leader, whether it is Miliband, Straw, Johnson, Harman or Uncle Tom Cobley, will be the need to seem unified, purposeful and new. Avoiding a Labour civil war means carrying the party. And that means pandering to the anti-Israel consensus.

The international context for a new leader will also be different. Although McCain is a resolute supporter of Israel, Obama's foreign-policy team is overwhelmingly hostile. Obama himself seems naively convinced that talking to terrorists and terror states will bring them to their senses, rather than acting as a demonstration of the West's spinelessness.

In the 1980s, Reagan and Thatcher spurred on each other's tenacity; in the 1990s, Bush and Major were steadfast against Iraq; and in recent years, Bush and Blair showed great resolve against terror. But Obama and a new Labour leader would, almost certainly, push each other in the opposite direction, feeding off each other's notion that Israel is the roadblock to peace.

The dynamics under Obama would be very different. Blair was constantly attacked as Bush's lapdog. In reality, they acted in concert because they simply agreed on the big picture. A weak Labour leader would, alongside Obama, be far more of a lapdog, with a limp UK foreign policy tugged along by an irresolute president.

The chances are, of course, that a new Labour leader would be a mere caretaker until being turfed out by the Conservatives. But there is little sign that David Cameron would be much different. As his Shadow Foreign Secretary, William Hague joined the anti-Israel bandwagon in 2006, criticising Israel's "disproportionate" behaviour in Lebanon. And Cameron himself has made a series of worrying speeches, not the least dreadful of which was made on the fifth anniversary of 9/11, in which he argued that recent foreign policy lacked "humility and patience" and that the US and UK viewed the threat from terror in "unrealistic and simplistic" terms.

The gloomy prognosis is that the chances of a new prime minister with a serious understanding of Israel and its place in the fight against terror are close to zero. Happy New Year.