Ross Lydall: MPs' expenses and Lib-Dem "dirty tricks"?

My, my, what have we here? The first evidence that an apparent cross-party consensus on not using the MPs' expenses scandal to score political points is breaking down?

Dropping through my letterbox yesterday was a letter from the "Pay It Back" campaign. It contains information about the claims of Dawn Butler, the Labour MP for Brent South, who has claimed around £60,000 in second-home allowances for a property in north-west London, despite having her main home in east London, an equal distance from Westminster. She has also been revealed to have overclaimed £2,600 in rent, and then offering to submit extra receipts to the Commons fees office "cover" the amount rather than simply paying it back.

The Pay It Back newsletter invites me to add my name to a petition calling on Ms Butler, who has shown a willingness to play the lackey to both Ken Livingstone and Gordon Brown, to pay back her second-home allowances. It says: "We find it appalling that a London MP who lives less than 30 minutes from Westminster can take thousands of pounds of taxpayers' money to pay for a second home."

Fair enough, you may think. The leaflet also contrasted Ms Butler's claims with those of Sarah Teather, the Liberal Democrat MP for Brent East (my local MP). Ms Teather has not claimed a penny in second-home allowances, and has been described by The Daily Telegraph as a "saint".

Then my eye caught notice of the small print. The leaflet (and campaign) is published by, erm, the Lib-Dems. At the next General Election, boundary changes will mean that Ms Teather will contest the new seat of Brent Central against.... you've guessed it, Dawn Butler.