LONDON -- Prince William and his wife Kate have helped broker deals at a finance firm's charity drive -- though they didn't emulate two male traders who donned hot pants as part of the colorful annual event.

The royal couple joined celebrities -- including the prime minister's wife, Samantha Cameron and actress Carey Mulligan -- alongside costume-wearing brokers at ICAP's charity day.

William and Kate helped close a deal on the Central European interest rate swaps desk before the prince asked broker Dan Lebeau about how he had sourced his costume of denim hot pants and 3-inch (7.6-centimetre) heels. Lebeau told him that "It was very difficult to find size 10 high heels in a normal shop."

Prince Harry took part in last year's event, which raised 8 million pounds ($12 million).