Hopkins was a boat salesman. He was making a test run of a hovercraft for a customer when Lupton, who was being pursued by the Third Doctor, knocked him out with his psychic powers and stole a speedboat. The Doctor arrived and borrowed the hovercraft. (TV: Planet of the Spiders)
Behind the scenes
The characters of Hopkins and his customer are split, renamed and redistributed in the novelisation. There, it is the customer, Mr Pemberthy, who tries out the hovercraft, whereas the owner of the boat yard, Bob Armitage, is watching from the shore. However, it is still the hovercraft tester, Hopkins in the television story or Pemberthy in the novelisation, who gets blasted by Lupton.