Jeremy Fullerton

In the novel Hallowe'en Party, Jeremy Fullerton is the senior partner of the firm "Fullerton, Harrison and Leadbetter" of Medchester. Fullerton was the solicitor of Mrs Llewellyn-Smythe who had died some two years before the events in the book. Her death was then followed by a controversy over a codicil to her will, subsequently shown to be a fake, that would have left everything to an au pair girl Olga Seminoff.

After the death of Joyce Reynolds, Poirot called on Fullerton with letters of recommendation from Inspector Raglan and Superintendent Spence. Fullerton had heard of Spence from the case narrated in Mrs McGinty's Dead and knew it had been solved through a Belgian, but did not associate that person with Poirot.

During Fullerton's interview with Poirot, he is surprised that Poirot does not focus on Joyce Reynolds but instead asked him for background information on Hugo Drake, Rowena Drake, Mrs Llewellyn-Smyth and Olga Seminoff. Poirot also asks him for information on a former employee of the firm Lesley Ferrier. Fullerton puzzles over how Poirot can think such long past events can relate to Joyce Reynold's death but nonetheless answers as fully as he can.

After the interview, Fullerton recalls an interview with Olga shortly after Mrs Llewellyn-Smyth had died. Olga thanked him for helping her with some issues in the past and wanted him to act for her in the matter of Mrs Llewellyn-Smyth's will. Fullerton had then told Olga he was unable to act for her because he was already repesenting the competing interests of the Drakes. Olga had protested that the codicil was genuine and properly  witnessed  by a cleaning woman and a gardener. Shortly after leaving his office, Olga had disappeared.

Portrayals
In the film adaptation of Hallowe'en Party in Series 12 of ITV's Agatha Christie's Poirot, Mr Fullerton has much the same role as in the novel. Here, however, he appears to be living in the village rather than in Medchester as he is shown attended the village church service. In the original, he knows about the fake codicil. Poirot and Ariadne learn that there is a real one but never find it. Here Poirot actually finds the real codicil and shows it to Fullerton, who remarks that it seems to be a much better attempt on the part of the forger (because it's real).

The part of Mr Fullerton is played by veteran British comedian Eric Sykes, in what would be his last television appearance.