Mr McMaster said: “After Bruce submits to Edward in 1302 he takes off the mail fist and puts on the velvet glove and arranges this political marriage. The Scots don’t swallow that for long, of course.
“Elizabeth was a young girl in her teens when they married in 1306 but things began to go horribly wrong for the king after he launches his rebellion. His sends his wife to Kildrummy Castle along with Marjorie and his sisters but the English bribe a blacksmith with gold to set fire to the corn store, allowing them to storm the castle.
“Edward rewards the blacksmith by pouring molten gold down his throat in a scene which could have come straight from Game of Thrones. The Bruce women are captured and his wife is imprisoned in England for eight years until after Bannockburn.
“Arguably, there were other women who played a more prominent role in his life such as Christina of the Isles, a Gaelic speaker who offered him shelter and men – and possibly more besides.
“With his wife in captivity he was not going to be a monk, not in that period anyway, so there’s undoubtedly one or two bastards we don’t know about.
“Then there was Isabella MacDuff of Fife, who rode up from England to put the crown on Robert’s head. The rumour was that she was infatuated with him and she was later imprisoned in a cage hanging outside Berwick by Edward as a warning to travellers.”
Dr Martin McGregor, senior lecturer in Scottish history at Glasgow University, agreed that Christina of the Isles may have been Bruce’s main love interest during the key years of his life.
“Women do play a significant part in his life and we know Bruce had a number of illegitimate children. A woman who was perhaps the mother of one or more of those children was Christina MacRuairi, from one of the main clans of the western seaboard. She was a key ally and we know that he was in her care, most likely in the Outer Hebrides, where he sheltered from the English and gathered his forces. It is interesting because Hebridean soldiery played a significant role and in battle Bruce was often to be found at the head of the men of Argyll and the Isles.
“If they are concentrating on the years from 1306 to Bannockburn and its aftermath then it would stand to reason the major female character wouldn’t be the queen because she was out of the picture, so perhaps Christina would be the most likely contender.”
Outlaw King is being directed by Oscar-nominated Perthshire film-maker David MacKenzie and producers want to take over Mugdock Country Park for 10 weeks in September and October.