Best of all, he was known for being grumpy. An image enhanced by the fact that he looked about 20 years older than he actually was. Journalists, whom he generally hated, called him "The Bear" on account of his grumpiness. He liked that.
During the 1967 season, Ford were busy promoting their new Formula Ford series. And, among the companies providing suitable cars for this championship, were Brabham. Who were also Denny's employers.
Somebody from Ford thought it would be a "really neat" idea if Brabham were to get one of their Grand Prix stars to demonstrate a Formula Ford car in front of the public at Brands Hatch. Jack Brabham owned the company, he didn't want to do it, and he didn't have to, so he didn't. Denny Hulme, as an employee, got the gig instead.
As well as the car, also on display here is an expression of utter disgust.