This one-off format would be copies for most of the drama series of the 70s and 80s and is still used today. Some one-off dramas started to be made, among them 'Lillie' the story of the King's mistress, Lillie Langtry starring Francesca Annis. 'Upstairs Downstairs' appeared for the first time in 1975 and is still, in my humble opinion, much, much better than the remake. 'Within These Walls' was copied later on by the Australian drama, 'Prisoner of Cell Block H'.
It was the top Saturday night drama, appearing after' The Generation Game' so that was your Saturday night sorted out - entertainment all the way. 1974 brought 'Within These Walls' a tale of the life inside if a fictional women's prison.