Route 1066

James Norton and Nikolaj Coster-Waldau play Harold Godwinson and William, Duke of Normandy, in a new drama about the bitter rivalry leading up to the Battle of Hastings

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Happy Valley star James Norton and Game Of Thrones' Nikolaj Coster-Waldau let their characters' rivalry turn into off-screen competitiveness while filming the BBC period drama King & Conqueror.

In the eight-part series, James plays Harold of Wessex, while Nikolaj is William of Normandy, aka William the Conqueror. They are two former friends destined to be on opposing sides in the 1066 battle for the English crown. James reveals that while Nikolaj is "a brilliant actor and a wonderful man", life began to imitate art as he felt the need to challenge his onscreen enemy when the cameras stopped rolling.

"We had Team Harold and Team William - we would jokingly spar about which storyline was more interesting," said James, 40. "We leant into the headbutting that Harold and William do in the script, and as a result, there was a gentle, boyish competitiveness between the two of us. We hung out a lot and went jet skiing - I remember racing him across the water and thinking 'this is very Harold of me'!"

The pair also spent time training together for the intense battle sequences, with both actors wanting them to be as authentic as possible.