Although the Secret Tube Station closed to passengers back in 1934, it used to be possible to get down to the platforms, although it's all locked up nowadays. The brief was to wear and old flying suit and to take a large ball of string and torch!
When they widened the Brompton Road in the early 1970s (can't remember the exact date), unfortunately the best part of the building was demolished. This was The Gladstone, where I quaffed the odd pint or two. It was also used by quite a few of the luvvies who used the Drill Hall for rehearsals, and the odd autographed photo or two adorned the walls.
Whilst the walk down to the platform and back might have helped Big Dave's jockstrappery, a few sherbets in The Glad' would have ruined all the effort!