It's the scene near the beginning of the movie where Price's character Edmund Lionheart, who is assumed to be dead after plunging into the Thames from a great height, washes up barely alive on a festering mudflat and is revived with a swig of meths by a gang of tramps who thereafter become his utterly devoted murderous minions for no reason at all. Nowadays there's a Theater of Blood Walking Tour, which pauses at the sacred spot for everyone to ceremonially swig pink fluid I assume isn't really methylated spirits.

And it's perhaps worth mentioning that, according to the movie Bedazzled (the 1967 original with Pete & Dud, not the appalling remake), God lives in the Great Conservatory at Syon House, where He is visited by Peter Cook's Satan.