AT 9.15AM on February 13, 1921, the sleepy peace of a Garnant Sunday was shattered by a woman’s scream.

As the village set about breakfast, Miss Phoebe Jones, head assistant of the Star Supply Stores, was roused by her landlord and informed that the shop’s rear door was open and the gas lights were still burning.

In an age when nothing but the chapel opened on a Sunday, Miss Jones knew something was seriously wrong.

She entered through the open door which led into a cellar store room and began to climb the short run of steps into the office and beyond into the shop’s main interior.

She immediately spotted the open safe and then saw the awful sight which forced that terrible blood-curdling scream from her lips.

Lying in a pool of blood behind the provisions counter was the body of Thomas Thomas.

The shop manager’s head had been bashed in, his throat cut open and a stab wound had pierced his abdomen.

The shop takings of £126 – roughly £4,500 today – were gone.

Beside Thomas Thomas’ body lay a block of cheese.

Embedded in it was his upper denture. The killer had seemingly used it to gag his victim, who had spat it out – false teeth and all – during the ordeal.

Despite the deadly wound to his stomach, Mr Thomas’ clothing showed no signs of damage. The killer had unbuttoned Mr Thomas’ trousers, lifted his waistcoat, shirt and vest and only then plunged the steel blade deep into flesh.

Once the act was done, the killer returned the clothing to its normal state, forgetting only to re-fix the top button of Mr Thomas’ trousers.

Dr George Jones, who carried out the post mortem examination, was in no doubt that each of the three wounds would have proved ultimately fatal.

However, it was his opinion that Thomas Thomas had been battered and then stabbed before his throat was slit, severing the carotid artery and the jugular vein.

The final wound caused almost instant death.

The presence of early-stage rigor mortis implied the deed had occurred between 10pm and midnight the previous evening.

The hunt to find the killer was under way with Det Sgt George Nicholls of Scotland Yard joining local officers to spearhead the investigation.

Nicholls learned that there were three doors into the store: the customer entrance on Cwmaman Road, the rear cellar door and a side entrance used by staff.

Nellie Richards, a 17-year-old assistant, had locked and bolted the rear door before leaving by the side door at 8.45pm. She had also locked the customer entrance.

Phoebe Jones had left at 9.45pm, locking the side door as she went and leaving Mr Thomas to work on the books. She too had checked the rear door was locked and bolted.

Without any sign of a break-in, one thing appeared obvious to Nicholls; the killer had hidden himself inside the shop and awaited Miss Jones’ departure before escaping through the rear door, away from the prying eyes of a bustling Saturday night on Cwmaman Road.

It was well-known that Thomas Thomas was of delicate health and partially deaf, making it a simple task for the killer to slip unnoticed from his hiding place and murder the conscientious shop manager as he balanced every penny.

The following day, two boys discovered a knife and a bloody broom handle in a nearby brook. The knife was identical to one missing from the store and the handle fitted a broomhead found close to Thomas Thomas’ body.

Despite the presence of the Scotland Yard detective and the discovery of the murder weapons, Thomas Thomas’ killer was never caught.

The murder of Thomas Thomas at the Star Supply Store on February 12, 1921, remains the Amman Valley’s most notorious unsolved crime.

And it is likely to remain so.