Mrs. Loftus returns to work as a nurse at the same time that Annabel, Lady Cornford's daughter, starts work. Annabel does not want preferential treatment and disguises her parentage but when she lets it slip that she has had dinner with the professor and has been seeing a married man called Geoff, it is assumed that she and Loftus are having an affair. Mrs. Loftus eventually explains the truth but, to save face, Duncan tries to tell everybody about another of the professor's indiscretions.

Professor Loftus is to go Buckingham Palace to receive his knighthood but rivalry between Waring and Bingham means that his Rolls Royce is cancelled. Duncan sets out to drive him but runs out of petrol and, when Collier offers to drive, Bingham lets his tyres down so that eventually the journey has to be made in an ambulance. Since some robbers have also used an ambulance as a getaway vehicle, confusion reigns as the hospital party is arrested. Sir Geoffrey misses his appointment but they do get a reward for catching the villains.