Britain's Prince Harry, Catherine, Duchess of Cambridge and her husband Prince William (L-R) raise their wands on the set used to depict Diagon Alley in the Harry Potter films, during the inauguration of Warner Bros. Studios Leavesden in London April 26, 2013.[Photo/Agencies]

Second in line to the British throne Prince William accompanied by his pregnant wife Kate and his brother Prince Harry on Friday visited the Warner Brothers Film Studio complex on the outskirts of London to mark its official opening.

The American film company Warner Brothers has invested 100 million pounds (154 million U.S. dollars) in developing the studio complex, where all eight of the Harry Potter films and the Batman series of films were made, since it bought the complex in 2010.

Accompanying Prince William was his wife, Catherine, Duchess of Cambridge, who is six months pregnant. They were welcomed to the site by Studio executives and Harry Potter author JK Rowling.

Prince William said he was "over the moon just to have seen the real Batmobile and Batpod (Batman's motorbike)" as the royal trio toured the studios before meeting 500 guests from 35 charities with which the princes are connected.

Prince William added that Prince Harry was pleased to see the talking owl from the Harry Potter series of films, also filmed at the Leavesden studios complex, and joked that Harry still did not know that Harry Potter was fictional.

Prince William, who is also president of the British Academy of Film and Television Arts (BAFTA) the film industry body in Britain, said that the Harry Potter film series was the most successful in film history.

The Prince ended his speech with a plea to Warner Brothers to "make another of the Dark Knight series" of films.