Complex sentence: Bale was not familiar with who Purvis was before making the film and "spent a great deal of time" with Purvis' son Alston and met other family and friends of Purvis, who died in 1960.
Split into simpler sentences: Bale was not familiar with who Purvis was before making the film. Bale "spent a great deal of time" with Purvis' son Alston and met other family and friends of Purvis, who died in 1960.