SIR Ian McKellen is to play an aged version of Sherlock Holmes in a new big screen film about the super sleuth.

The Lord of the Rings star is once again teaming up with his Gods and Monsters director Bill Condon in a movie adaptation of the Mitch Cullin novel A Slight Trick Of The Mind.

The former Bolton School pupil, who also played Magnito in the X-Men films, has been cast as an older version of the detective, who comes out of retirement to crack an unsolved case from 50 years ago, involving an angry husband and his unstable wife.

In the story, based in 1947, Holmes is losing his memory, and without his sidekick Dr Watson, the famous Baker Street detective can only remember fragments of what has happened.

He is faced with the toughest case of his life that might finally reveal to him the mysteries of the human heart.

The film’s executive producer Aviv Giladi said the combination of Sir Ian and Mr Condon was “a perfect match for this clever and intriguing project”.

The 74-year-old actor, who began his career at Bolton Little Theatre where he is now a patron, has had a busy 12 months — he will return as Gandalf in the new Hobbit film later this year and in another X-Men instalment, Days Of Future Past, in 2014.

In recent years Sherlock Holmes has been portrayed by Benedict Cumberbatch in the BBC One modern update of the Sir Arthur Conan Doyle stories, and has also been played by Robert Downey Jr in two films.

Jonny Lee Miller has also portrayed him in US TV series Elementary.

Director Mr Condon is currently at the Toronto International Film Festival for the world premiere of his new film, The Fifth Estate, about Wikileaks and its founder Julian Assange.

A Slight Trick Of The Mind is expected to start shooting in the UK in April next year.