By Ian Youngs
BBC News Online entertainment staff
The King Arthur movie is an "authentic" portrayal of history, one of the film's historical advisors has insisted.
Clive Owen (right) plays King Arthur in the new film
The film, released in the UK on Friday, has had criticism for claiming to be "the true story behind the legend".
"That came from the ad department, not the producer," according to historical consultant Dr Linda A Malcor.
"The producer of this film wanted to make everything as authentic as possible, which he went out of his way, often at great expense, to do."
The story has come under fire from some experts for portraying Arthur as a 5th Century half-Roman, half-British warrior in Cumbria.
Stuart McHardy, author of The Quest for Arthur, has been quoted as saying: "I think that Hollywood's idea is driven by Hollywood's love of money and not by any knowledge base whatsoever."
Many think of Arthur in a more regal, medieval setting, and some historians believe he was based in Scotland, Wales or Cornwall.
"I think these film-makers did a better job than most could have done when it comes to giving us something besides knights in tin foil and damsels in chiffon," Dr Malcor said.
"The story created by (screenwriter David) Franzoni is fiction, but, as with all good historical fiction, it draws heavily on historical facts.
"We probably would have had a lot less negative press if we'd shown a Celtic king Arthur, riding to the rescue out of Wales, but I just don't think that happens to be the truth behind the legend."
Clive Owen plays Arthur - based on the story of Roman soldier Lucis Artorius Castus - while Keira Knightley is Guinevere and Ioan Gruffudd stars as Lancelot.
The film-makers acknowledge that the real Lucis Artorius Castus lived in the 2nd Century and they moved the action forward 300 years.
"Some creative licence was taken with a few of the details, but that happens in all storytelling, and what is a movie if not another way of telling a story?" Dr Malcor said.
Film-makers did "everything they could" to take her advice when possible, she added.
"I've absolutely never encountered that sort of openness to a researcher in Hollywood in the 20 years I've been in the business.
"I think the film-makers deserve a lot of praise for the effort that they made."
But Geoffrey Ashe, who wrote The Discovery of King Arthur, has said: "There is simply no evidence for it.
"Make no mistake, I'm not saying there is little evidence for it, I'm saying there is no evidence."