Although Tim Sewell is credited with writing the screenplay from an original story by director Henry Cole, shortly before the start of principal photography, Cole himself rewrote some sections of the script to bring out the British upper-class eccentricity which he felt was missing.
One of the editors, Sidney Levin, previously cut the Joe Cocker concert film, Mad Dogs & Englishmen.
The Drug Squad officer was originally to be called MacKenzie but was renamed Stringer at a late stage because there was a real-life MacKenzie at Scotland Yard.
Patrick Lichfield: the photographer taking a family portrait of the Dyer family at their country seat.