 He was one of a group of underwater clearance divers who checked for limpet mines in Gibraltar harbour during the period of Italian frogman and manned torpedo attacks by the Decima Flottiglia MAS.They dived with oxygen rebreathers, Davis Submerged Escape Apparatus, which until then had not been used much if at all for swimming down from the surface.At first they swam by breaststroke without swimfins.