Mayor's £16.50 claim for poppy wreath while he was an MP

Today Mr Johnson said the cost of the wreath had been "mistakenly added" to his expenses forms. The fees offices rejected the claim.

The Mayor added that he had "happily" paid the cost out of his own pocket when he was denied the refund.

A spokesman said Mr Johnson had been unaware of the claim in 2006 but an invoice sent by Thame town council has been passed on to the fees office by a member of staff.

As an MP, he was also paid mortgage and council tax costs of nearly £100,000 for his designated second home in his former constituency of Henley in Oxfordshire.

During his time as a Westminster politician he claimed a total of £85,299 for his second home allowance, including the maximum in his last two years.

At the time Mr Johnson was an MP his main home was a £1 million family house in Islington.

However, rather than a bolt hole in his constituency Mr Johnson's Henley home was described to the Standard as a "sprawling farmhouse" complete with swimming pool.

Despite the maximum claim, a source said the mortgage on the house was so large the taxpayer had only paid for two-thirds of the cost of the mortgage and Mr Johnson had paid the remainder.

Today Mr Johnson said: "Voters outside London rightly expect their MPs to have a home in their constituency. I bought a family home in Henley, more than 50 miles from the House of Commons, for that reason, and I spent a considerable amount of time there with my wife and four children.

"South Oxfordshire is one of the most expensive areas in the UK for property and my claims under the second home allowance covered only a proportion of my mortgage interest payments.

"I have not sold the house nor changed its designation. I claimed my council tax and utilities, but otherwise did not claim a single thing - not even a bath plug."

The Mayor still owns the farmhouse near Henley which he visits "when he can" but his family have since moved to a £3 million property in one of the most expensive roads in Islington.

Mr Johnson first moved to Oxfordshire in 2001 when contending Michael Heseltine's former seat.

Initially he rented a house in the village of Swyncombe and at the time said: "We were thinking of getting a houseboat, but after all the flooding I thought our houseboat might end up in someone's front room."

As an MP Mr Johnson earned £64,766 in his final year in 2008 but also declared outside earnings of between £340,000 and £405,000.