He had accumulated the biggest private collection of gorillas and used to wander around his private Kent estate "Howletts" quite naked and swim with his Siberian tigers in his pool. Great chap. I spent periods of time with "Big John" over many years. Fond memories and numerous scratches from playing with the tigers, on one occasion, a half dozen of them at a time! He taught us to do a strong purr through our mouths to imitate a tiger friendly sound they make to each other.
I only went in with him inside a large caged area with a single young gorilla and one of his keepers - once - and he and the gorilla would swing each other around in what was a terrifying scenario because of the animal's strength. If the gorilla got too carried away, John would give it a few hard thumps to establish he was the boss. Though it could have torn him apart with little effort.
As an "unfamiliar" to the animal I kept out of the way as much as I could - even that took some courage when the gorilla would take a look toward me as if deciding whether to play and wrestle with me, too. I can still see those excited eyes which had no intended meanness but spelled severe physical damage if I got chosen to "dance" as once happened. John and the keeper rushed to my rescue and saved me from more than minimal contact.