During his later life he was a founder of the Fortress Study Group, a prominent member of the Concrete Society, and a dedicated fund raiser for the Red Cross.
Shortly afterwards the company was transferred to the 51st (Highland) Infantry Division and stationed in the Saar region to gain experience on the Maginot Line.
As a result of his efforts, Hamilton-Baillie was moved to Oflag VII-D at Tittmoning, a medieval castle on an isolated plateau in Bavaria, Germany.
Finally, Hamilton-Baillie was moved to Oflag IV-C (Colditz Castle) from which he made a number of attempts to escape but remained incarcerated until liberation by the 69th Infantry Division (United States) in April 1945.
After a series of senior administrative roles in the Middle East and Germany, his final appointment was as Brigadier Engineer Plans in the Ministry of Defence during which he was aide-de-camp (ADC) to the Queen between 1972 and 1974.
Hamilton-Baillie retired from the army in 1974 and spent the following 10 years as lecturer in soil mechanics and geology at the Royal Military College of Science, Shrivenham.