The Milner family moved frequently following World War II, the result being that Dan grew up in far-flung localities including Birmingham, Ballybunion, Toronto and Brooklyn.
The latter was a member of the police (Garda Síochána) and drowned while on holiday in Ballybunion, Co. Kerry July 1940 and acted as Boyle's father following the death of his mother 1933.
Spring is a member of Ballybunion Golf Club, and has invited former U.S. President Bill Clinton, amongst others to this location.
Ballybunion has reprinted The Assassin's Handbook, as well as the original works Assassin's Handbook 2, The Movie That Never Was (a screenplay he and Richard Sapir wrote for a Destroyer movie that was never optioned), The Way of the Assassin (the wisdom of Chiun), and New Blood, a collection of short stories written by fans of the series.