In the novel Three Act Tragedy, Robin Babbington was the late son of Rev. Stephen Babbington and Mrs Babbington. He had been in India, and was killed there. Hermione Lytton Gore tells Mr Satterthwaite that she had "rather a pash on Robin".
Robin is not mentioned in Ustinov film Murder in Three Acts (1986).
In the ITV David Suchet episode Three Act Tragedy (2010), Robin is mentioned by "Egg" several times. He was not dead at the time of the events in the show. Here Egg told Poirot that she once "had a pash" on Robin but when she rejected him, he "went mystical" and left for India to live at an ashram.