Julian Fellowes investigates a most mysterious murder on BBC One, Saturday, October 16:

IT WAS a gruesome killing which scandalised Victorian society but even Agatha Christie could not piece together the clues. Now Julian Fellowes, the Gosford Park Oscar-winner, claims to have finally solved the murder of Charles Bravo.

The London murder in 1876 had all the elements of a Christie mystery. A high-flying barrister lay poisoned, taking three days to die. The suspects included his beautiful heiress wife, her physician lover and a stableman who bore a grudge and guarded a supply of poison.

"It electrified the country and exposed the dark side of upper-class Victorian society," said Mr Fellowes, whose screenplay for Gosford Park was based on a real-life murder.

There were so many suspects that a coroner’s court concluded that the finger of guilt could not be pointed at one individual. The events have been recreated for a BBC One film next weekend which examines the motivation and opportunity for each of the suspects to commit the murder. Mr Fellowes presents a new conclusion which he believes will finally put the baffling matter to rest.

Mr Bravo, 31, an ambitious barrister tipped for a parliamentary seat, was killed by a lethal dose of antimony tartrate administered in his Balham mansion. Victorian detectives suspected his rich, hard-drinking wife, Florence Ricardo, who had escaped one abusive marriage to find herself in another with the autocratic Mr Bravo. She had pursued an affair with James Gully, physician to Charles Dickens and Benjamin Disraeli, who was twice her age and who had made her pregnant and performed an abortion. She was ostracised. Marriage to Mr Bravo gave her a second chance at social legitimacy but it also made Dr Gully very jealous. For Mr Bravo, the marriage offered a hope of access to Florence’s money.