It was developed by John Hawkesworth and starred Anthony Andrews as Lieutenant Brian Ash, an officer in the Royal Engineers (RE).

As with all his fellow officers, Ash must for the most part learn the techniques and procedures of disarming and destroying the UXBs through experience, repeatedly confronted with more cunning and deadlier technological advances in aerial bomb fuzing.

Brian is restored to active service but when he is promoted to captain and transferred to what seems a meaningless position in Somerset, he feels useless.

Hartley's book, a non-fiction memoir of technical information and anecdotes, provided some of the major story developments.

Chapter 8 covers the Grimsby Raid of June 13, 1943, which forms the basis for "Butterfly Winter" and includes the development of the string-and-pulley system for moving the SD2s about, the bombs in the bean field, and the inspiration for Sergeant James being blown off the stone wall and breaking his arm.

Many of the bomb-disposal scenes were filmed in what appeared to be deep, freshly dug holes lined with wooden shoring (the way real bomb disposal often happened).