The pair - along with a string of stars who became brokers for the day – jokingly manned phones and closed multi-million pound deals.
The brokers in fancy dress – including Batman and Robin – roared with laughter as the royal heirs sealed one deal worth £14billion, declared the biggest foreign exchange deal to date.
At one point a Finnish shipping executive offered William – who is set to marry Kate Middleton on April 29 – his daughter’s hand in marriage as an incentive.
As the 28-year-old royal chatted to Ben Lundqvist about the offer, his father Prince Charles attempted to seal a deal with oil company Shell a few feet away.
The heir to the throne joked: "Sorry about this I've no idea what I'm doing. My son seems to be involved in an endless conversation."
He then shouted to William: "Is he offering you a wedding present?" to which the room collapsed into laughter, as the prince replied: "He's asked me if I will marry his daughter."
The royal duo toured several departments at global firm ICAP in London, which donated the day's revenues to more than 200 good causes.
