It was broadcast in the early 1980's on Radio 4. The plot was about a spaceship that was on a mission to look for planets to colonise. The adults had all been killed in some kind of accident and the only survivors were four children. The computers were called 'Angels' and I think they had gone mad (a bit like Hal in the film 2001) and were evil. I can't remember anything else but I know I enjoyed it and would like to find out if it has been released on CD. Many thanks.