Complex sentence: Filming took place in the United Kingdom; exterior scenes were filmed at Ashridge Park, Buckinghamshire, and because the filmmakers considered it too dangerous and time-consuming to shoot in an actual cave interior scenes were filmed on sets built at Pinewood Studios near London.
Split into simpler sentences: Filming took place in the United Kingdom; exterior scenes were filmed at Ashridge Park, Buckinghamshire, and because the filmmakers considered it too dangerous and time-consuming to shoot in an actual cave. Interior scenes were filmed on sets built at Pinewood Studios near London.