The story of the Cambridge spy ring, the group of notorious British double agents who passed secrets to the Soviet Union, is to be turned into a "sympathetic" TV drama by the BBC.

The four-part series will tell how Guy Burgess, Donald Maclean, Kim Philby and Anthony Blunt were recruited at Cambridge University and went on to become some of the most effective spies of the Cold War.

Philby became MI6's head of counter-espionage

The BBC says it wants the audience to be able to sympathise with the spies, whom it will portray as "incredibly glamorous".

A spokeswoman said it would be a "fresh" take on the story, and that it was the first time the story of the group as a whole had ever been tackled by film-makers.

Philby, who became head of counter-espionage operations for MI6, will be played by Toby Stephens, an actor who will soon be seen as a villain in the new James Bond film.

It will also star Gosford Park and Enigma actor Tom Hollander as Burgess, Timothy West's son Sam as Blunt, and Rupert Penry-Jones as Maclean.

The script is about "friendship, passion and conviction", according to producer Mark Shivas.

Sam West is the son of Timothy West and Prunella Scales

"It's about how far they were prepared to go to realise their ideals, and their unshakeable faith in their beliefs."

The programme will show that although they betrayed their country, the group firmly believed that what they were doing was right and that fascism was the enemy.

Written by Peter Moffat, it will also explore their unease at the Duke of Windsor's connections with the Nazis.

"Peter Moffat has drawn out its contemporary resonance for a modern audience focusing on their steadfast belief in communism and the passions that drove them to betrayal and huge personal sacrifice," BBC controller of drama commissioning Jane Tranter said.

The series will be called Cambridge Spies, and will begin filming in September in England, Spain and the United States.