Princess Anne is renowned for her love of horses and was the first member of the British royal family to compete in an Olympics, in eventing in 1976.
Speaking to Sporting Life, Mike said that his wife Zara and mother-in-law Anne are die-hard racing fans.
"[Zara] loves it - she loves horses in general, but from the racing side of things it's always been a massive part of her life. The Princess Royal is also a die-hard horse racing fan.
"I think it's great for the profile of the sport to have her in it, and she loves her role at Cheltenham now. She's hosting people every day and she loves it."
Zara looked chic in an olive green coat from Hobbs with a blue patterned dress by Really Wild, tasselled boots from Fairfax & Favor and a Fedora-style hat by Victoria Charles.