Another Hidden London tour – this time under Euston. I can still feel the dust in my nose. We looked at a former tube tunnel that was taken out of service when the island platform between two tube lines became too narrow for safety. Then the old tunnel linking two rival underground lines (whose separate entrances were either side of the mainline station) where there was a shared underground ticket hall. This tunnel was closed in 1962 and the walls are still layered with advertising posters from then. They have decayed but – given the lack of light – they are still vibrant.

The tour was full of interesting little things – e.g. making it easy for people to change trains by having platforms adjacent for popular connections is hazardous when the trains don’t arrive and depart in tandem. It’s actually safer to manage hordes of passengers by making them walk some distance to make their connection. I learned that the Luftwaffe bombing of Guernica in 1937 prompted the British government to prepare for the possibility of air raids; there was a control room just off the tunnel, and air raid warden service was established that year.

I also discovered that the oxblood-red building at the end of Drummond Street I’d noticed before was the station for the Charing Cross, Euston & Hampstead railway from 1907-14. Designed by Leslie Green, it has been used as a ventilation shaft ever since, but it is soon to be demolished to make way for HS2. I shall have to take a photograph before I leave.