When they extended the Jubilee line into South London, all the new platforms had PEDs - Platform Edge Doors, which divide the train tracks from the platform, and prevent suicide attempts, as well as improving air circulation and reducing pollution - both noise and litter.

The tube pulls into the station and aligns with the doors precisely, and then both sets open, allowing people to pass easily from tube to platform. But when there's no tube in the station, the PED is a glass wall, reflecting the waiting commuters back, darkly.

This is P and I, tired on a Sunday morning at Waterloo. We were on our way back from a wedding in the country, waiting for the train to carry us home, to bed.