Michael Martin, the Commons Speaker, will be asked by MPs from all sides to explain why his wife has claimed about £1,000 a year in taxi expenses even though she is not employed by Parliament.

Mary Martin claimed £4,280.20 for taxis since May 2004, which were “entirely in connection with household expenditure that supports the Speaker’s duties”. According to the Speaker’s spokesman, she needs to take taxis to shop for food for official functions.

Some MPs are surprised and irritated that such a high amount of public money has been spent to support what is an unofficial role, especially as their own expenses on taxis are restricted.

Under the rules MPs can claim 40p a mile, rather than the full amount. Their spouses can claim for 15 return journeys a year by public transport but partners are barred from claiming for taxis. Special arrangements are made for ministers’ spouses.

Mrs Martin claimed £1,317.93 in May 2004-April 2005, £1,057.29 in 2005-2006, £972.79 from 2006-April and £932.16 between April and December. The House authorities said: “She is always accompanied by an official from the Speaker’s office in this task. The average cost is less than £40 per week over the weeks that comprise the parliamentary year.”

One source familiar with the arrangement said that the Speaker should be seen as in the same bracket as ministers. The source explained that when Mrs Martin, who essentially lives in Glasgow, appeared in Westminster she was often required to act as a hostess at dinners in honour of foreign speakers. She had, the source said, extensive duties over the course of the year, and as such, £40 a week was not substantial, but the arrangement could be reviewed if there was anger about it.

Mrs Martin’s claims are in addition to her husband’s, which average about £400 a year since May 2004. He also has a chauffeur-driven car, which has cost the taxpayer just under £20,000 a year over the same period.

Mike Grannatt, a spokesman for Mr Martin, justified Mrs Martin’s claim. “She goes shopping for food and so on for entertaining official visitors. The Speaker entertains periodically. There is a budget that is held for the Speaker’s office and the money comes from that,” he said. He confirmed that Mrs Martin was not employed by her husband in any capacity.

According to a freedom of information request made by The Times in June, the Speaker hosted six dinners in the state rooms last year at the cost of £10,869.33 and spent a further £44,216 on entertainment. “This includes the cost of receptions for external visitors and delegations, and the cost of annual receptions within Parliament,” the FoI request said.

The Martin household’s expenses as Speaker are very low.

Mr Martin submitted £745.37 in expenses in his role as Speaker in 2006-07 and £324.11 since the beginning of this financial year. His wife is entitled to claim “minor expenses incurred in connection with the maintenance of the Speaker’s official household” but has not claimed anything in 2½ years, according to a FoI request released on December 13.

A large Sainsbury’s is close to Parliament Square and the Oxford Street branch of Marks & Spencer will deliver food to the front door.

Norman Baker, of the Liberal Democrats, said: “All of us in the House of Commons have a duty to use public money carefully . . . If any public money is to be used by spouses or partners of MPs there has to be a particularly good reason and it has to be tightly controlled.”

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