In the novel Sad Cypress, Mr Edmund Seddon was the solicitor of the late Mrs Welman. His firm has offices at 104 Bloomsbury Square.
After Mrs Welman's death, Mr Seddon tells Elinor Carlisle and Roddy Welman that she had never made a will. He explains that he had frequently advised Mrs Welman to make a will, but she had always said that there was plenty of time, and that she did not intend to die just yet. He says that because she died intestate, all her property would go to her next of kin, Elinor.
Mr Seddon later advises Elinor in drawing up a schedule of sums of money to be given to the servants, and in making provision for Mary Gerrard. He also advises her on matters regarding the sale of Hunterbury.
After Elinor is arrested, Mr Seddon tells Poirot that although his firm does very little in criminal procedure, he felt that it was his duty to the late Mrs Welman to undertake the defence of her niece.