He meets Freya whilst on holiday, and begins an affair with her. Just before he departs for Barcelona to report on the Spanish Civil War, Lottie unexpectedly visits his London flat and quickly realises another woman lives with him. On his return to England, following an acrimonious divorce, he marries Freya in Chelsea Town Hall. The newlyweds move to a house in Battersea where Freya gives birth to their daughter, Stella. During the Second World War, Mountstuart is recruited into the Naval Intelligence Division by Ian Fleming. He is sent to Portugal to monitor the Duke and Duchess of Windsor; when they move to the Bahamas, Mountstuart follows, playing golf with the Duke and socialising regularly until the murder of Sir Harry Oakes. Mountstuart suspects the Duke is a conspirator after two hired detectives ask him to incriminate Oakes' son-in-law with false fingerprint evidence. Mountstuart refuses and is called a "Judas" by the Duchess. Later in the war, Mountstuart is interned in Switzerland for two years. After the war's end, he is grieved to discover that Freya, thinking him dead, had remarried and then died, along with Stella, in a V-2 attack.