In the 70s I worked as a electrician servicing many of the London pubs.
Several of them adjacent to the Thames have 'smugglers tunnels' which were used for transporting contaband from the river to the cellars.
One of the most fascinating pubs was not far from Wellington Barracks in Hyde Park.
I arrived to do some lighting repairs and as I opened the door to go down the cellar one of the customers shouted out "Mind the ghost".
The story I got was that the Duke of Wellington was so unpopular with his men that he had a tunnel dug from the barracks to the pub so he wouldn't have to walk the darkened streets late at night. The tunnel is said to be haunted by the ghost of a soldier who was flogged to death for attacking the duke late one night.
I also worked in a pub in S E London where I was to repair faulty cellar lights. When I arrived I was asked had I brought a ladder - I had a short stepladder on my van. I was told that this was not anything like tall enough.
I found that the pub was built over an abandoned railway tunnel and at one time the ceiling of the tunnel had collapsed. Rather than repair it the company had built a staircase down to the extremely deep tunnel floor.
Jim Carroll