The Sweeney - Season 2 Episode 1 Chalk and Cheese

Giles Nunn and Carrie Selhurst are an upper crust couple who, partly for kicks and for the profits, commit highway robbery in lonely country lanes, along with the lower class boy Tommy Garret, whose dad is a friend of George Carter. Regan is on to them and Carrie gets arrested, but her unwillingness to cooperate leads to the death of the next victim.