Last week we reported that Dame Margaret had been censured by the parliamentary standards commissioner for using her Commons office for her review of the Garden Bridge project, for which she was paid by City Hall.
On Monday Dame Margaret used a point of order to make an apology in the Commons chamber.
"I would like to sincerely apologise to the house for inadvertently acting in breach of our code of conduct when I used parliamentary resources during my independent review of the Garden Bridge."
She added: "I acted in good faith and in the public interest but I fully accept the judgments of the commissioner and the committee on standards and I have repaid the sum of £2.97 – representing the cost of House of Commons stationery – to the House of Commons administration."
The Garden Bridge project has so far cost taxpayers £46 million.
Dame Margaret has estimated that if the scheme had gone ahead the cost to the public purse could have topped £100 million.
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