On Easter Sunday, 1978, Arthur Brough's wife of fifty years passed away. Brough was so distraught that he immediately announced that he was quitting the business. Jeremy Lloyd and David Croft opted to keep Brough's character of Ernest Grainger open in the hopes that Brough would change his mind. Arthur Brough passed away a matter of weeks after his beloved wife on May 28th, 1978. Lloyd and Croft decided to retire the character of Grainger, and created the replacement character of 'Mr Tebbs' that was played by veteran actor James Hayter.
This was Arthur Brough's final television appearance before his death on May 28, 1978 at the age of 73.
"Spike Milligan jumping through the bottom of a boat" refers to a 1973 Benson & Hedges cigarette commercial. It contained no dialogue and starred Milligan and Peter Sellers.
The "radio mic" Mr Lucas gives to Mrs Slocombe is just a cut off lapel microphone with no transmitter and therefore, useless.