Back home in Ramsey village, in Essex, from a brief caravan holiday in Scotland, Alison Morris, 25, was delighted to find she had been accepted for two jobs as a university lecturer – one at Salford, the other at Liverpool. Tragically, she was unable to take up either.

On Saturday, September 1st, 1979, she went for a walk down to the nearby River Stour before a planned quiet evening at home with her parents at their home in Wrabness Road. She would be back in 20 minutes, she said, to watch a Michael Caine movie on TV. That too was not to happen.

For as she walked down a lane towards the river a hand appeared from behind her and covered her face. She couldn’t have screamed even if there had been time. With incredible viciousness her attacker stabbed her repeatedly in the front and back of the chest with a single-bladed knife.

The murder was baffling because there was no sexual assault and no robbery. That, according to the police, made it the work of a man who was “totally deranged.”

At one stage a man in his 50s, about 5ft 10 ins, with a small beard and wearing a long, light-coloured trench coat, was being sought. Police also wanted to interview a young couple seen kissing and cuddling in a car parked by the main road at about the time Alison entered the lane. None of these people came forward.