In the TV show, Bickerstaff’s Mansion is a spooky, derelict house called Silwood Manor – a grand Victorian country house and estate, some way out of town in Berkshire. It is currently part of the campus of Imperial College London, specialising in ecology, biology, pest control and other countryside sciences. It’s not wholly unlike Bickerstaff’s mansion as depicted in the books, but we can’t visit as the 1870s manor house is not open to the public. There are enough photos and video on the internet of it to make clear that it’s the initial interior and exterior location for the gang’s night-time adventure. The scenes in Bickerstaff’s basement itself were shot on a studio set.

In the books, we are told Bickerstaff’s sanatorium (clinic) is located on the edge of Hampstead Health. It is situated at the end of Whitestone Lane in Hampstead, where the road runs out and there’s a wild section of Hampstead Heath beyond. It’s hard to see much, though, because the road becomes a private lane and it’s not possible to walk too far down. To get more of a feel of the area, you can walk further down East Heath Road past Whitestone Lane and then turn left into Vale of Health, which is a small community of houses deep in a forested area of the heath. – and that’s very much what Whitestone Lane is like in real life.

Bickerstaff’s Mansion would have been in good company. Due to the the clean air and peace, the “Vale of Health” was a popular place for doctors ready to provide health cures.