In the novel One, Two, Buckle My Shoe, Alistair Blunt is a high-profile banker, "the head of the greatest banking firm in England". He lives at the “Gothic House” on Chelsea Embankment, and also has houses in Kent and Norfolk.
Alistair is described as being a "very quiet and retiring man", and a "quiet nondescript Englishman". He is known to live a quiet, unobtrusive life, never appearing on a public platform or making speeches. He is fond of golf and his garden.
According to Mr Morley, Alistair always came to his appointments "absolutely on time", and often sent his car away. He would then walk back to his office after his appointment.
Alistair met Rebecca Arnholt when she came to London. At that time, he was a junior partner of the London house, and was sent to Claridge's to see her with some documents. They married six months later.
The marriage was a success, to everyone's surprise. It had been thought that Alistair, who was twenty years younger than his wife, was only marrying her for her money, and that he would spend her money on other women. However, he remained quietly devoted to her during her lifetime, and did not marry again after her death.
Alistair is known to have a genius for finance no less than that of his wife's. His judegments and dealings are sound, and his integrity is "above question". He is able to dominate the Arnholt and Rotherstein interests by his sheer ability.
Alistair is with the Prime Minister when they are shot at while leaving 10, Downing Street. The bullet misses, but is believed to have been intended for Alistair instead of the Prime Minister.
Alistair later invites Poirot to spend the weekend at his house in Kent. On the way there, Alistair tells Poirot that he reads a lot of thrillers and detective stories, and he is interested in hearing about Poirot's cases. He also asks Poirot to find Mabelle Sainsbury Seale.
Alistair also tells Poirot that in the event of his death, most of his money will go to the St Edward's Hospital, the Cancer Hospital, and the Royal Institute for the Blind. He has also left some money to Julia Olivera, an equivalent amount in trust to Jane Olivera, and some to Helen Montressor.
Alistair shows Poirot his garden, and points out certain minute and rare species in the rock garden, which is his greatest joy. Poirot is also with him when a shot is fired, and Frank Carter is found with a pistol in his hand.
Poirot suggests that Mr Amberiotis found out about Alistair's secret from Miss Sainsbury Seale, and attempted to blackmail him. Alistair killed Mr Morley so that he could pose as a dentist, and give Mr Amberiotis an overdose of adrenaline and novocaine. The real Miss Sainsbury Seale had also been killed, and Gerda posed as her. The dental records were also falsified so that the body would be thought to be that of Mrs Albert Chapman.
After Poirot tells Alistair that Helen Montressor has been arrested, Alistair confesses. He tells Poirot that he and Gerda enjoyed the secrecy of their relationship, and that he eventually passed her off as his cousin, after the real Helen Montressor passed away.
Alistair tells Poirot that something had to be done, because if he was ruined and disgraced, England would be affected as well. He says that he has held England firm and kept it solvent, and that he believes that he is necessary to the continued peace and well-being of the country. He suggests that Poirot quietly retire from the case. However, Poirot refuses, and Alistair is arrested.