Mr and Mrs Expenses to face investigation

Home-row MPs Ann and Alan Keen are under official investigation over their expenses, it was announced today.

The Labour couple dubbed Mr and Mrs Expenses are being questioned over claims they milked the parliamentary expenses system by listing an empty property as their main home.

Two weeks ago squatters moved into the constituency house they claimed was their main residence - which had apparently not been lived in for a year.

Standards commissioner John Lyon agreed to a formal inquiry after studying allegations that their main and second home declaration was inaccurate.

The Keens have charged taxpayers £40,000 for a second home even though it was only nine miles away from their main address. Under Commons rules, an MP's main home is usually where he or she spends the most nights.

The pair have been married since 1980 and represent neighbouring London constituencies, Mr Keen at Feltham and Heston, while Mrs Keen, a health minister, is MP for Brentford and Isleworth.

They bought an apartment overlooking the Thames near Westminster for £500,000 in 2002 and were said to be claiming for interest on mortgages worth £520,000. They have claimed £137,679 in the past four years.

The Keens insisted they were only temporarily staying full-time at their second home while renovations took place. They are taking legal action to evict 10 squatters. Mrs Keen said: "We had no choice but to halt work on our home because we became very concerned about the quality."