The Duchess of Cornwall joined brokers at the global firm ICAP on the company's annual charity day, now in its 25th year.
The high-powered brokering desks, where multi-million pound deals are made, were transformed into a party atmosphere by the elaborate fancy dress costumers staff wore.
Her Royal Highness stopped to say hello to the characters Sonic the Hedgehog and Shrek, magical leprechauns, zombies and even inflatable giant pandas.
During an hour spent on the brokering floors in the City of London, The Duchess completed a number of deals raising thousands for good causes.
Among the other famous faces also closing deals were actor Kelsey Grammer, known for his roles in US sitcoms Cheers and Fraiser, rapper Professor Green, Olympic gold medallist Sir Chris Hoy, former England footballer Rio Ferdinand and Dragons' Den star Deborah Meaden.
At the desk dealing with New Zealand dollar swaps Her Royal Highness took to the phone to complete a 60 million dollar deal, with the help of Ms Meaden, which raised thousands.
Phil McMahon, a senior broker on the desk, said: "She was wonderful, she did very well.
"It's difficult to pick up the phone and speak to someone you don't know and make a deal."
ICAP is an inter-dealer broker that matches buyers and sellers who want to trade in a range of products and The Duchess was taken around the desks putting the finishing touches to transactions by chatting to clients.