Roger Curbishley
Roger Curbishley was the son of Lady Eddison and Colonel Hugh Curbishley. Arnold Golightly was his half-brother on his mother's side.
He was a proper gentleman, conducting himself politely in public and flirting with women. He was actually homosexual and had a secret relationship with one of the servants, Davenport, meaning the Curbishley/Eddison line might end with him. It appears his father and the head butler knew of this, but kept it a secret.
In 1926, he attended his mother's party with honoured guest Agatha Christie, where he met Donna Noble and the Tenth Doctor, who immediately noticed his relationship with Davenport. At dinner, he was stabbed in the back by his half-brother, the Vespiform known as Arnold Golightly. His death was avenged when Donna Noble killed Arnold to save Agatha Christie. (TV: The Unicorn and the Wasp)