He made and lost fortunes in gambling, owned four exclusive London casinos: the Clermont Club, Aspinall's Club, the Aspinall Curzon Club and Aspinall's; and had two private zoos in Kent, Port Lympne Zoo Park and Howlett's Zoo Park, which have seen a number of maulings and accidents to keepers and visitors, including five fatalities. He, together with the brothers Sir James and Teddy Goldsmith, founded the Ecological Foundation and its magazine, The Ecologist, in 1972.