Rock the Polo takes place during the day of the Cartier International Polo tournament, being held at Guards Polo Club in Windsor on 27 July.
According to joint managing director Jules Stevenson, GSP will redesign the event, previously managed by Hype Party Planning, in a bid to improve its overall flow. Stevenson also promises to "up the ante" on entertainment.
After a four-month pitch process, Stevenson was delighted with the win. "If you're an event producer this is the Mecca of the event world," he said.