It showed on Sunday nights on ITV (not BBC2) in 1983.
From the TV Cream site, though I remember this as a six-part series: "SCRIPTED play about two scouse kids Billy and Icky (DAVID MORRISSEY, SPENCER LEIGH) running off to go camping in Wales where they are befriended by a school teacher who wis staying there. Much of the programme is dedicated to the development of the relationships between the teacher and the boys. One becomes jealous, nicks a Ford Granada and drives back to Liverpool at breakneck speed, killing both boys in a car crash on a bridge."