IT'S been described as "the weird little brother" of Game of Thrones and as a hallucinogenic 21st century take on 43AD Britain. But now historical drama Britannia is creating divisions between historians worthy of the feuds of tribal Celts themselves, with some claiming that its depiction of early Britons is "offensive gibberish" based entirely in fantasy with others singing its praises.

Although some experts on the period have forgiven the "hilarious" gaffes of Sky's latest epic drama series, claiming it is "a marvellous yarn", others told the Sunday Herald that the "fantasy" depiction of Celts was disrespectful. The naysayers claim it betrays an entrenched discrimination against the Celts who are written off with flippant disregard, with Romans are treated with careful historical accuracy.

The nine-part drama is set in the mid-1st century and follows the Roman army who, after Julius Caesar’s failure to conquer Britain, return to crush its Celtic heart. It tells the story of a land ruled by Celtic warrior kings and queens – and populated by feuding tribes and devil worshipping druids – that don't go as quietly the Romans had hoped.

Simon Rodway, a lecturer at the University of Aberystwyth, claimed that while Roman characters are based on real historical figures – such as politician and general Aulus Plautius, played by David Morrissey – the Celts were fantasy figures. Zoe Wanamaker plays a fictional Queen Antedia while Mackenzie Crook is Veran, another fantasy Briton.

Rodway, an Celtic expert originally from Edinburgh, said: "My objection to this is the double standard. The Romans were given perfectly plausible Latin names, but the Britons were called things like Veran, Pellenor and Gildas. There are databases containing hundreds of authentic Brittonic names from the period at which the series was set which are freely available on the internet.

"The fact that the researchers couldn't be bothered to get the Brittonic names right is indicative of a widespread attitude that the Celtic languages and their speakers are not really important. No serious person need bother about them, any more than they need to have a working knowledge of Tarot or yoga. They are the preserve of cranks and fantasists.

"But of course there are plenty of Celtic speakers out there – Welsh, Irish, Gaelic, Breton, Manx and Cornish –who are often on the receiving end of this sort of attitude, whose cultures are belittled and ignored even in their own communities. They and their ancestors deserve to be treated with the same respect as the 'great' civilisations of Rome, Greece et al."

Acclaimed play and screen writer Jez Butterworth, who created the script with his brother Tom, has admitted that he is relaxed about the fact that it is likely to enrage sticklers for historical accuracy, while other academics told the Sunday Herald that it was far from a simple matter of a few historical errors.

Historian Dr Alex Woolf of St Andrew's University claimed many details were "outlandish". Although Celts in the early episodes are seen to be cave dwelling he claimed in reality they would be living in thatched houses surrounded by arable fields. Depictions of their religious beliefs were about 1800 years out of sync with reality, he added.

"They might as well have sent the Romans to Westeros [the fictional continent in Game of Thrones] in terms of accuracy," he said. "We academics set a high bar when it comes to drama, I do accept that. But this isn't like a colleague saying they wouldn't have used that type of chair in Jane Austen's time. It is like everyone on the set of a Jane Austen drama being dressed as it they lived under the reign of Elizabeth 1. It's essentially complete gibberish.

"It seems that when it comes to the Celts anything goes. If [programme makers] tried to do the same with native Americans it would be seen as racism, but there is a sense that you can get away with anything when it comes to the Celts. I think it's disrespectful. Some people are very offended by it."

However Richard Alston, of the University of London, said that the more realistic depiction of the Romans were understandable as information about them was "more accessible", claiming that several important themes were concealed within Britannia's crowd-pleasing script. Although he admitted the chances of a colony of druids living over the hill from a Celtic village, as depicted by writers, was "very remote".

He added: "What I think is being dramatised is a sense of a mystic understanding of the world which is then ripped asunder by the imperial power." He claimed a diversity of voices were heard in the drama. "For most imperial stories," he said "we only have one end of the narration, that of the imperialists. It is really important to think about those other perspectives and those silenced voices, the women, the slaves, the conquered, whose views are not recorded. Imaginative and dramatic reconstruction is one of the best ways of getting to those voices."

However Alistair Moffat, leading Scottish historian and writer, said that "hilarious gaffes" -– including the skinning of a rabbit that would not have been found in Britain at that time and the proliferation of rune symbols not on historical record until 150AD – matter "not one whit".

"The way in which the Celtic kingdoms of the south of England are realised is nothing short of brilliant," he added. "This is not a documentary. It is a marvellously conceived yarn that creates what I suspect is a very close approximation to what Britain was like 2,000 years ago."

A Celtic timeline

1,400 BC – The beginning of Celtic culture in the upper Danube region of central Europe.

900 BC – Celtic migration begins in Europe with many Celts landing in Scotland.

700 BC – Iron Age begins in Scotland.

335 BC – Treaty between Celtic tribes and Alexander the Great

58-51 BC – Julius Caesar leads the Romans in the Gallic Wars. In 55BC he invades Britain

39AD – Caratacus (1st century British chieftain of the Catuvellauni tribe) leads the British Celts

43AD – Emperor Claudius launches a fresh attack to subdue the Celts in Britain