In February 1917 Captain George Bruce took over an audacious British Military Intelligence espionage ring, the headquarters of which was located at 41 Rue St Roch in Paris. The organisation recruited and trained French and Belgian refugees and sent them back into German occupied territory to collect intelligence on enemy troop movements, especially in train watching. The intelligence was coded and fed back to an office in Folkestone, in Kent, where it was used to work out the enemy order of battle and provide advance warning of reinforcement – which could also herald an imminent offensive.

In 1921 Major George Bruce inherited the title of the 7th Lord Balfour of Burleigh and held the title until his death in 1967. His son, Lord Robert Balfour, succeeded to the title and later married Dr Janet Morgan, who then became Lady Janet Balfour of Burleigh, she is a renowned military historian and wrote (amongst others) a book about the intelligence activities in the Rue St Roch. Lady Bafour became a Vice Patron of the Military Intelligence Museum in 2014.