The Commons Standards and Privileges Committee ruled they designated a house as a second home while actually using it as their main residence.

The couple, who represent neighbouring constituencies in west London, were "equally responsible for ... a serious misjudgement," the Standards Commissioner found.

However the committee said it would take a more lenient view as Mr and Mrs Keen had a "long run of bad luck" due to "difficult circumstances beyond their control".

The MPs designated a property in Mrs Keen's constituency of Brentford as their main home and also kept a flat nearer Parliament.

In May 2008 they began building work on their main home which overran. It was eventually boarded up and the Committee found they did not sleep there for nine months.

The Department of Resources told them they could keep making claims, the report found.

However the Committee decided that because one of their properties was uninhabitable, they effectively only had one home and breached the rules by claiming for a second residence.