Mensch quitting gives Labour byelection hope

Within five minutes of Tory MP Louise Mensch announcing she is quitting her highly marginal Corby and East Northampton seat to go to the US with her rock 'n' roll husband and family, the Twittersphere was alive with speculation about this being a golden opportunity for Ed Miliband and Labour to gain the Tory constituency in the byelection.

It was only natural that the former chick lit novelist Louise Bagshawe should explain her decision to quit at this awkward time for her leader, David Cameron, in a series of tweets.

Mensch is an habitual tweeter and has spent a lot of her life making punchy political points in under 140 characters.

This morning she told her followers: "It has proved impossible to balance the needs of my family. I (have) written to the prime minister. This will be published in due course...."

One of the first to reply was Labour's Tom Watson, a fellow member of the Commons culture committee who often clashed swords with Mensch in his chase for the truth behind the News of the World phone hacking scandal.

He avoided saying he would be sorry to see her go. Instead he said: "You're a remarkable character Louise. Be all you can be."

Mensch told Cameron in her letter she had found life a strain since marrying her second husband Peter Mensch, the New York-based manager of Metallica and the Red Hot Chili Peppers, last year.

"As you know," she wrote to Cameron, "I have been struggling for some time to find the best outcome for my family life, and have decided, in order to keep us together, to move to New York. With the greatest regret, I am thus resigning as a Member of Parliament."

The Daily Telegraph is reporting this morning that the byelection will be a "headache for the party" in a highly marginal seat - previously held by Labour - in the middle of the "always-volatile" post-conference season of November.

Cameron gave a clear hint that he had hoped to promote her into the government - possibly in the reshuffle that is coming in September. "It goes without saying that I had wished to see you serve for longer and at a more senior level".

Mensch had earned promotion by keeping her nose clean and being loyal when it mattered. Crucially she backed culture secretary Jeremy Hunt when his job was on the line during Miliband's attack on Hunt for getting too close to the Murdoch empire.

Within minutes of the Mensch announcement, the Labour candidate Andy Sawford tweeted: "Fired up, ready to go."

With a majority of just 2,000 and Labour in a double-digit lead in the opinion polls, it would be a terrible blow to Miliband's credibility if he can't take the seat now. No pressure there then, Ed.