'The Crown' star Jason Watkins feels as though he has a "duty of care" to research his characters who are real people

Speaking at the world premiere on the new series in London, Watkins said: "I tend to do a lot of research as a duty of care to that person and their family, particularly if they have passed away."

The 'Line of Duty' star wanted to portray Wilson accurately as he will be a familiar figure to older viewers who remember his two tenures as Prime Minister from 1964 to 1970 and 1974 to 1976.

He said: "He's such a familiar figure, particularly to the older generations, that one has to capture that. There's lots of studying and just instinctive impersonation. There are also traits such as where he's from and what his belief system is. He's a very principled person and I wanted to share that."

Watkins also feels that the grand scale of 'The Crown' meant shooting the programme felt like being a movie set and said that each episode is like a mini "film".

He explained: "The scale of it means it feels like you're on a film set, each episode is a film in itself and has a beginning, middle and end. It has these wonderful intertwining stories. It is very clever and brilliant writing."

Watkins also opened up about the relationship between Wilson and Queen Elizabeth, who is played by Olivia Colman in this series, claiming that the Labour politician was on "unfamiliar ground" with the monarch, who was suspicious of him.

He said: "In our historical interpretation he was on unfamiliar ground. The Queen has a view of him thinking that he may have been connected with the Russians. She's suspicious of that.

"Harold Wilson was a fast talker with a sharp mind, it was a matter of tempering that with the surroundings and how he was going to approach this relationship with her majesty."