By-election test for Tories as Louise Mensch stands down as MP

Louise Mensch, the high flying chick lit author and Tory MP, shocked Westminster today by announcing that she is resigning from Parliament because of the pressure that politics puts on family life. She is moving to New York with her three children to join her husband, Peter Mensch, manager of the rock band Metallica.

Her departure is a blow for David Cameron, who is now faced with a by-election in Corby, which was a Labour seat for 13 years until Mrs Mensch took it with a majority of just 1,951 in 2010. The by-election is expected to be held on 15 November

In a very short parliamentary career, Mensch has become almost a household name because of her confident television performance and adroit use of the social media. She was a combative debater and a fierce defender of the government and, in her role as a member of the Commons Culture, Sport and Media committee, she set herself as a defender of the beleaguered Murdoch media empire.

She was, nonetheless, popular with political opponents in the Commons, who respected her as a hard -working MP who was not afraid to speak her mind. That contrasted with the furious reactions she often stirred up among members of the public who disagreed with her.

A Twitter star, with over 102,000 followers, she was also a target for internet trolls. In June, 60-year-old Frank Zimmerman received a suspended prison sentence for sending her a threatening e mail.

She was well known as the chick-lit author Louise Bagshawe before becoming an MP, changing her surname when she married Peter Mensch in June 2011.

Her departure is a symptom of the stress of imposed on parents of young children trying to pursue a political career. MPs say that the lasting impact of the expenses scandal has made it harder for those with young families representing constituencies out of London. In the past, they could claim the cost of second class train fares for spouses and children to travel between London and their constituencies, but that is no longer allowed.

Writing to the Prime Minister to announce her resignation, Mrs Mensch said: "As you know, 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 MP."

Mr Cameron replied: "It is with enormous regret that I accept your resignation as the MP for Corby and East Northamptonshire, a seat that had been Labour for thirteen years before you," the PM said. "I do so only because I wish to support you in acting in the best interests of your family, which must come first."