Spencer, a former Conservative Party treasurer and close friend of David Cameron, founded London-based ICAP, one of the world's largest interdealers. In 2015 he sold its voice-broking and information division to Tullett Prebon in a £1.3bn merger that saw the new group called TP ICAP, with Spencer receiving a 9% stake. He sold most of it for £200m earlier this year, retaining a holding worth £21m. The rest of the ICAP operation was renamed Nex Group, where he remains chief executive and has a stake valued at £348m.
Spencer previously made £79m selling his spread-betting group City Index and past ICAP share sales add at least £90m, though the full scale of his winnings from the Tullett deal have not been made public. Spencer, 62 at the end of the month, was nominated for a peerage last year by Cameron, but this was blocked amid the fallout from the Libor rate-rigging scandal when ICAP was fined £55m in 2013 by regulators. While serving as a party treasurer it is estimated that Spencer raised more than £100m for the Tories. Through his IPGL business he gave the party more than £107,000 last year. ICAP's charity day in December 2015 was boosted by the presence of the Duke and Duchess of Cambridge, helping to raise £7.5m for a variety of good causes.