 The sailing scenes at the "Botel" were filmed on Grafham Water, Huntingdonshire.The film was meant to screen at Cannes, with early buzz indicating that it would be a festival favourite and go on to become a sleeper hit; it never showed there due to the May 1968 events in France, and, failing to make an impressive premier, went on to an only mediocre performance at the UK box office.Horror journalist Preston Fassel, in his biography of Vanessa Howard, noted this was the first incident in a string of unfortunate coincidences for the actress, whose career was continually derailed by circumstances beyond her control.