Before I describe my stay at The Arch London, an establishment steeped in the history and grandeur of London’s ‘Upstairs Downstairs’ era, first a story.

I have to confess my heart sank a little when I first walked into the lobby of the Great Northern Hotel at Kings Cross Station. Don’t be alarmed when I tell you it was a little on the sociable side. In fact, with me, my luggage and the four members of the lobby team grouped around the tiny reception desk, I felt we were all on the rush hour commuter special.

Careless talk costs lives. You never know who is sitting next to you, who is listening. For the chilling core of the 20th Century, Second World War to Cold War, St Ermin’s was the cloak-and-dagger hub of international espionage.