The cost of Boris Johnson's accommodation for his New Year's holiday was covered by the co-founder of Carphone Warehouse, David Ross.
Mr Ross is named in the MPs' register of interests as donating £15,000 towards the PM's private Caribbean break with his partner, Carrie Symonds.
Mr Ross was one of Mr Johnson's aides in City Hall and was appointed to the Olympics organising committee.
But he resigned from the roles, and his company, over a share scandal in 2008.
It emerged Mr Ross had used millions of pounds worth of Carphone Warehouse shares as collateral against personal loans without informing the company's other directors - a potential breach of City rules at the time.
