Bryan is described as an "amiable-looking young man of thirty-odd with brown hair, rather plaintive blue eyes and an enormous fair moustache". Lucy Eyelesbarrow says that he is rather sweet, and that he is "like a dog that wants to be taken for a walk".
Bryan likes Lucy, and is frequently in the kitchen with her. On one occasion, he is "watching her with a kind of dog-like attention". He also occasionally helps her with the cooking.
Bryan was a fighter pilot during the war, and has a D.F.C. He says that because of that, people try to make things easy for him, and offer him jobs. However, the available jobs are all administrative jobs, which he is not good at. He has business ideas of his own, but has had difficulty getting investors.
Lucy says that Bryan's schemes all sound rather wonderful, but they are not practical. She thinks that he never considers the actual working difficulties. She also says that all his schemes are air schemes.
Bryan likes Rutherford Hall because it reminds him of the big rambling Victorian house he lived in when he was a boy. He says that one could land a plane quite easily in the park. He feels that he and Alexander could be very happy living there, and that it seems like a waste for Cedric to inherit the house, as he will just sell it.
Bryan is initially not considered a suspect, as Elspeth McGillicuddy had said that the murderer was a tall dark man, and he is fair. However, Lucy realises that his hair can look dark from behind, because he plasters it down with hair products. Miss Marple says that she had considered that.
In BBC's 1987 adaptation of 4.50 from Paddington, the part of Bryan Eastley is played by David Beames. In the adaptation, according to his son Alexander, Bryan was a highly successful fighter pilot during the Second World War. He had 24 combat victories and was awarded the D.S.O with bar and the D.F.C. with bar. Eastley became an insurance agent after the war, but not a successful one. One of the running gags in the show is him always somehow ending up doing whatever Lucy Eyelesbarrow says. So when Lucy says he should not sell products he doesn't believe in, he quits his job. Later, in a fit of annoyance, she tells him to do anything, sell you house, buy a plane.... Eastley really mortgages his house and buys a small plane. Eastley dislikes Cedric Crackenthorpe because he is a rival for the affection of Lucy. He tells the police that he saw Cedric at Northolt Airport on the day Anna Stravinska was murdered, thus destroying his alibi that he was in Ibiza. At the end of the show Eastley pairs off with Lucy Eyelesbarrow, just as is strongly suggested in the book.