The phone call to Scotland Yard was precise and to the point: “We broke into a mill house near Chelmsford and tied up an old lady. You had better release her.” Then the line went dead.

By the time Essex Police, alerted by the Yard, had found the “mill house” – in reality a cottage – the old lady, Susan Southgate, 83, was already dead. She had been bound and gagged with electric flex and was sitting in her favourite leather armchair at her home in Writtle, near Chelmsford.

She was known locally as a wealthy woman who paid her bills from a roll of £50 notes. Living alone she was an easy target – even so, the thieves missed £5,000 in coins.

There were some clues. A chisel and two reels of insulating tape stamped with the words FOOTPRINT, ENGLAND, were found in the cottage. A black Humber saloon was sighted at about 10.45 p.m. on the night of the murder, Thursday, April 17th, 1958.

And there was a possible suspect. A stranger was seen in the village on two nights during the week – a man with nicotined fingers and black, oily hair. He had a couple of beers at the Cock and Bell pub in the village on consecutive nights before the murder, but was not seen again after it.

Whoever killed Susan Southgate was also suspected of tying up and robbing an elderly farmer who lived about 15 miles away.