By Sarah Mills

LONDON (Reuters) - A young Princess Elizabeth ascending to the British throne is the focus of new Netflix series "The Crown", a royal drama looking at the early reign of the UK's longest serving monarch.

Set in post-World War Two 1947 Britain, the show begins with Elizabeth and Philip Mountbatten's wedding before the princess inherits the crown at age 25 when her father King George VI dies.

British actress Claire Foy, who starred in drama "Wolf Hall" last year, plays Elizabeth and "Dr Who" actor Matt Smith portrays her husband, the Duke of Edinburgh.

"I think you already know what the limits are and what you have to achieve in a way," Foy told Reuters about taking on the daunting role. "I felt that I had to get certain things right in order to allow for the more creative and sort of interpretive side to be legitimate really."

Netflix has invested in two seasons of "The Crown", which was written by "The Queen" scriptwriter Peter Morgan. His team of researchers went through archives, biographies, cabinet minutes and conversations Morgan had with people linked to the royal household for the show, which mixes true events with fiction for more personal moments.

Episodes feature key moments such as the queen's coronation and look at her relationship with former prime minister Winston Churchill, played by "3rd Rock from the Sun" actor John Lithgow, and her sister Princess Margaret's romance with their father's equerry Peter Townsend.

"(Morgan) allows you to peak behind this royal veil that we all are aware of...and that's really engaging emotionally and interesting," Smith said.

The 10-episode series, released on Friday, was shot in southern England, Scotland and South Africa. Media reports have cited a budget of 100 million pounds ($122 million) for the show.

"You couldn't have made a show about this family...without spending money on it," Foy said.

"I would love to think she (Queen Elizabeth) would watch it as I think she would love the coronation, I think she would love the royal wedding, I think she would love Matt's Philip...But...it's too weird to think that she would watch it." ($1 = 0.8185 pounds)

(Editing by Jeremy Gaunt; Writing by Marie-Louise Gumuchian)