Long before that, ZM73 had another roll for film sent to him by Doctor Jacob Seltzman. This roll of film he left at the World Camera shop on Victoria Colonnade in London. The developed prints to be made into slides. The proprietor gave ZM73 a receipt for the roll of film. The receipt he gave to his fiancée Janet Portland for safe keeping, in time of trouble. However, seeing as how Sir Charles Portland could have been able to obtain that receipt from his daughter, and thereby the slides which had been made up from the photographic prints. Might not it have been safer for ZM73 to have put the receipt in the wall safe behind the television set in his study? Thereby removing the need for the character of Janet Portland from the episode, which would then have required a different title!
Be seeing you