On Tuesday, July 20, 1999 at 8:00:00 AM UTC+1, Phil Clark wrote:
Isn't there an underground subsurface station somewhere that has a big
pipe with the Tyburn in it running above the platforms next to the
passenger footbridge? It might even be Baker Street BICBW

You are wrong. It's Sloan Square Station. The sewer pipe was damaged by a bomb in WW II, resulting in raw sewage flowing into the station.

And I have a suspicion that it's not the Ty Burn, but is actually the King's Scholars' Pond sewer ? BIMBW ;-)