A GREAT-grandmother who was exposed at the age of 87 as one of Soviet Russia’s longest-serving spies in Britain has inspired a new film.

Red Joan, which comes out this weekend, stars Dame Judi Dench as a character based on Southampton-raised Melita Norwood.

An agent for more than 40 years, she passed on secrets that were said to have brought Russia’s atomic bomb project forward by two years.

She was born Melita Sirnis, in Bournemouth, in 1912, to a Latvian father and British mother.

Her father produced a newspaper which printed articles by Lenin and Trotsky, and he attracted Communist Party members to the family home.

Melita went to West End School and Itchen Secondary School.

She then studied Latin and logic for a year at Southampton University before moving to London to find a job.

She joined the Communist Party and married chemistry teacher Hilary Nussbaum, the son of Russian parents.

Her husband, who changed his surname to Norwood, disapproved of her activities, Melita said years later.

After becoming a spy, she passed her handlers secrets which came across her desk as secretary to the director of the British atomic weapons project.

Her espionage was not publicly revealed until 1999, by KGB archivist Vasili Mitrokhin, who had defected seven years before.

The widowed spy was still living in the home at Bexleyheath in London that she had shared with her husband.

“In general, I do not agree with spying against one’s country,” she said.

But she added: “I did what I did not to make money but to help prevent the defeat of a new system which had at great cost given ordinary people food and fares which they could afford, good education and a health service.”

Norwood, who was never prosecuted for her actions, died aged 93 in 2005.

Documents released in 2014 suggested she may have been even more valuable to Soviet intelligence than the Cambridge spy ring that operated in the 1940s and 50s.

Norwood’s story was fictionalised in Jennie Rooney’s novel Red Joan, the basis for the new film in which Dame Judi Dench and Sophie Cookson share the lead role.

Norwood herself was said in 2001 to be working on a book.

Asked about the possibility of her life story becoming a film, she said: “There have been a lot of silly offers.”

The film which is directed by Trevor Nunn is due to be released on Friday.