Jonah, Iain, re Gordon Brown’s numbers nosedive, I think the truth lies somewhere between your respective points. As Iain points out, under the Westminster system, the Prime Minister usually wears out his welcome before the party does. But the trick then is to replace him with someone who can plausibly claim to be fresh. Nobody had heard of John Major until he emerged as Mrs Thatcher’s replacement. He was so new he seemed to have been cooked up for some particularly implausible rags-to-riches novel: son of a trapeze artist, former bus driver, etc.

The Blair/Brown succession is much closer to what happened in Canada a couple of years back, when a long-serving and (in party terms) successful Prime Minister (Jean Chretien) was forced to make way for a long-serving and supposedly popular finance minister (Paul Martin). The finance minister then turned out to be just as stale and exhausted as the tired old predecessor but not half as popular. Result: change of government. It’s like Johnny Carson retiring in favor of Ed McMahon.

The exception to this trend, I think, might have been had John Howard handed over to his long-serving (and ostensibly unpopular) finance minister, Peter Costello, three or so months back. But we will never know.

We now return from you from our 24/7 Commonwealth Election Watch to your regularly scheduled Rudy’s-girlfriend security-detail budget update.