Michael Cassidy, the former leader of the City of London Corporation, says he was approached by Lord Archer, the millionaire novelist and Conservative constituency cheerleader, with the job offer. "He suggested I might want to be his deputy," said Mr Cassidy, who is contemplating putting himself forward as an independent candidate.
According to Mr Cassidy, Lord Archer said he could choose from one of five portfolios to be created if he became mayor: environment; planning; transport; economic development; and public health. Mr Cassidy was told that a sixth portfolio, police, had already been filled.
Mr Cassidy said he found Lord Archer's offer all the more remarkable since no details have emerged as to how the mayor will be chosen, and the Tory party has yet to anoint Lord Archer as its official choice.
The author's determination to become the capital's mayor has seen him appoint a campaign agent and launch a publicity drive. His relentless quest was displayed on the country's television screens on Boxing Day when he appeared on the Dame Edna Everage show to promote his interest in the job.
But it comes amid growing evidence of a "stop Archer" campaign among senior Tories at Conservative Central Office and on the influential 1922 committee of backbenchers. They are thought to be unhappy at the prospect of him receiving the party's nomination and are considering putting forward Chris Patten, the former Hong Kong governor and ex-Tory chairman, as an alternative. But senior Tories acknowledge that if the party's ticket is decided by grassroots members, then Lord Archer stands a strong chance.
Neither of the possible frontrunners from the other main parties, Ken Livingstone from Labour and Simon Hughes from the Liberal Democrats, is making such a concerted effort at this early stage.
Lord Archer said last night his conversation with Mr Cassidy was private and he had no comment to make.