Michael Spencer is by now probably better known for his political and philanthropic work than for his pre-eminent position in one of the City’s least appreciated but most profitable sectors. Every December Icap, the interdealer broker that he founded on a shoestring with a few friends from the City in 1986, stages a high-profile charity day in which all profits go to a range of deserving causes.

It is attended by celebrities from the worlds of showbusiness and sport and, most recently, an occasional member of the Royal Family. At this year’s event, Prince Harry conducted a telephone trade and in all £11 million was raised. Others in attendance included Boris Johnson, the London Mayor, the actors Patrick Stewart, Richard Wilson and Jennifer Saunders, and Greg Rusedski, the tennis player. Since its inception 16 years ago the affair has raised £53 million.

Mr Spencer is one of the City’s richest men, although it is not a label he welcomes. He has been treasurer of the Conservatives since last year and is known to be close to David Cameron and George Osborne.

He has always insisted that he is devoted to Icap, where he is chief executive, and has not discussed any political ambitions. But those who know him believe that he will play some significant part in any future Cameron administration, possibly as a working peer.

Highly gregarious, he is known for his hospitality and knowledge of fine wines. Mr Spencer and his wife, Lorraine, recently announced their separation after 25 years of marriage.