The journey enabled them to try out one of London Underground’s new S-Stock trains, which are being introduced to 40 per cent of the tube network. The walk-through, air-conditioned trains are built at the Bombardier facility in Derby.

"It was an honour to have The Prince and The Duchess visit us today and help us mark the 150th anniversary of London Underground and the enduring importance that the network has to London and to the UK economy," said Mike Brown, managing director of London Underground & London Rail. "As we mark the anniversary we are also building for the future – transforming stations and replacing trains, signals and track. Our passengers are already seeing the benefits, with more frequent and reliable services on the Jubilee and Victoria lines among many other improvements."