I hope they haven't got any spare bedrooms

In total, the 71 MPs claimed £926,159.75 of taxpayer cash to cover mortgage interest over the 15-month period

http://www.guardian.co.uk/politics/2013/may/09/mps-told-repay-profits-homes

For those without a calculator, that means the average claim per MP over 12 months was £10,435.60.

Or about equilvent to a years minimum wage. 

Or twice the average Housing Benefit Claim.

The largest claims made by Labour's Michael Connarty – who received £34,168 relating to a property in London. Surely here's one MP who won't be supporting the benefits cap ?
David Miliband claimed £5,903 on a property in his former seat of South Shields. Well he's not short of a few pounds. The House of Commons register reveals that he has ben paid nearly £1 million – from outside interests since losing the party leadership to his brother, including £125,000 for 15 days’ work as a director of Sunderland football club owned by a super-rich businessman with interests in private equity. Approximately £60,000 has come his way from the UAE, a gulf state with an unappetising human rights record, and another hefty chunk from St James’s Place, a company that advises very rich people how to invest their money.

Greed pure and simple - the only explanation of why he would be claiming what to him is such a triffling sum.