Strangers.

Strangers is a 1978–82 ITV police procedural created and principally written by Murray Smith, based on characters created by Kenneth Royce in his novel series and subsequent 1977–78 television adaptation The XYY Man. Don Henderson and Dennis Blanch reprise their roles, respectively, of Detective Sergeant (DS) George Bulman and Detective Constable (DC) Derek Willis. A group of police officers are brought together from across the country to the north of England. There, the fact that they're not well-known gives them the advantage to infiltrate where a more familiar local detective could not. Despite being based around a comparatively small team of detectives, a regular feature in its early years is that few episodes feature the entire team, with most using just two or three regulars in any major role.