Heartbeat - Season 7 Episode 14 Substitute

Alf has to deal with a group of travellers who have a grudge against him. Alf is determined to catch them at whatever crime they're about to commit. He feels guilty for not convicting them of a crime they committed in the past during which one of his old colleagues was crippled. Alf spends time observing them and making notes, but unfortunately he is spotted and they take him and tie him up in a horse box. It is a race horse that they intend to steal, but during the process Alf makes his escape and drives off in the horse box. They follow him but road blocks have been set up and the thieves are caught. Greengrass lets some guides camp on his land but it proves more hassle than he bargained for.