The speaker of the House of Commons, Michael Martin, faces a new investigation into his expense claims.

John Lyons, the parliamentary commissioner for standards, has begun a preliminary investigation into Mr Martin's expenses.

The speaker has faced criticism over his wife's £4,280 taxi bill, which he maintains were only used for official business.

His aide, Mike Grannatt, resigned in February after admitting he inadvertently misled journalists.

He said he had himself been misled by "people who knew the facts," although maintained the speaker was not involved.

Mr Martin is himself leading a Commons inquiry into MPs' expenses.
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