You can never go wrong watching Edward Woodward as the tortured but oh-so-capable assassin - and using a proven TV storyline for expansion was a savvy move as well.
The big problem with 1974's Callan appear to come from a shoe-string budget that caused some real problems.
The worst is the fifth-rate musical score that frankly steps all over the scenes in which it is used. The inappropriate harmonica is particularly grating and you cheer for the sequences without the ill-fitting music.
The sets seem pretty squalid too with a 3rd-rate school gym housing the training ground for England's top assassins.
But stick to the acting and story and it's a fairly diverting yarn.
The film is tough and diverting as Callan wrestles with his conscience and the demands of his section. Fun to see Peter Egan playing against type as a psycho-bully as well as David Prowse from Clockwork Orange and Star Wars.
Finally, the film features a rare chance to see tabletop wargaming on screen - a hobby both for Callan and Woodward.
