Plot hole: When Danny Kendall first appears in series 9 (1986) he is in the third year, then the fourth year in series 10 (1987) but in series 11 (1988) he is put down a year to help him catch up with work he missed as he was in hospital for most of his fourth year. But in series 12 (1989) he is in the fifth year when he would be aged sixteen going on seventeen and he would not be legally obliged to stay on at school, as sixteen was the legal school leaving age then. When Danny died in series 12 the school planted a tree in his memory with a plaque in front of it giving his birth date as 8th January 1973 and death date as 22nd January 1989. His birth date should have been 8th January 1972, as he would have been seventeen years old when he died.