Until now, though, it was unclear what form this extreme act had taken. Some suggested the individuals had been consumed not for nutrition, but as a homage to the spirits of the dead. Others floated the possibility of “crisis cannibalism”, where fellow humans were eaten in the throes of hunger and desperation during a harsh winter.

The latest analysis, focusing on a single radius bone, partially resolves this question by suggesting that there was at least some element of ritual in the gory proceedings.

The study describes for the first time decorative zigzag incisions on the bone that appear to have been carried out between the butchering process and consumption.

Chris Stringer, head of human origins research at the Natural History Museum in London, who was involved in the original excavation and also the latest research, said: “This wasn’t just a case of someone dies and then they’re eaten. The process is interrupted halfway through. They’ve cleaned off the flesh, then someone sits down and very carefully carves this design and only afterwards do they break open the bone to get the marrow out.”

Microscopic imaging and comparisons with other incisions suggest that the patterns were purely decorative and not carried out for the purposes of butchery.

“This is the first time this kind of pattern has been seen on a human bone from this time period,” said Stringer. “We’re confident that this is not functional, but it’s specially done with some symbolic meaning.”

The latest work, published in the journal Plos One, follows previous work describing a series of polished “skull cups” found at the cave, which could have also formed part of an elaborate death ritual. The scientists are not sure whether the skulls – which appear to have been turned into drinking vessels – and the butchered bones belonged to the same individuals, but hope to answer this question in the future through DNA testing.

The cave-dwelling cannibals were among the first humans to recolonise Britain after the last ice age. After the ice age ended around 14,700 years ago, tribes of hunter-gatherers moved into Britain from Spain and France across a land bridge that is now submerged.

The dates of remains at Gough Cave suggest the cavern was populated for more than 100 years during this period, and that the early humans would have hunted deer, boar, horses and hare.

Silvia Bello, a palaeontologist at the Natural History Museum in London and the study’s first author, said: “It’s something that we find horrifying, but … that was their tradition. Like we incinerate bodies or put them in the ground. It was their way of disposing of bodies, like it or not.”

An analysis of the bones show that almost 40 per cent of them feature human bite marks and 60 per cent of the remains showed some signs of butchery. “It implies that they were maybe really hungry,” said Bello. “There’s no bites on any of the skull remains, but the feet and hands are very much chewed.”

However, there are no signs of the remains having been directly burned, suggesting that if they were cooked at all, they were probably boiled.