I went to see blockbuster The Imitation Game and found my dad was a war hero!

A teacher only realised the true extent of her dad’s Enigma Code-cracking secret life while watching a hit movie starring Benedict Cumberbatch.

Sherlock star Cumberbatch, 38, plays Alan Turing, the man behind the Second World War Enigma project in the movie, The Imitation Game.

Primary school teacher Jane Smith, 54, of St Andrews, Fife, went to see the film knowing her dad, John Harrison, had been involved in code breaking during the war.

But she was unaware that he was part of such an exclusive team, whose heroic exploits inspired the film.

John, who died in 2012, was head-hunted to join the codebreaking team while he was an economics student at Cambridge University.

At the time, in the early 1940s, Britain was losing the Battle of the Atlantic and was on the verge of being occupied by Germany.

Geniuses were needed to crack the highly cryptic code Germans used to communicate with their U-boat submarines.

John was among a team recruited to work with master genius, Alan Turing, at Bletchley Park HQ in Buckinghamshire.

They were bound by the official secrets act and forbidden to utter a word of their mission.

True to his word, John kept most of his work secret until his death, aged 90. He only mentioned brief details to Jane, her two brothers and her sister.

“He said he had been recruited after one of his university lecturers asked him to quickly complete a tough newspaper crossword,” Jane said.

“But we didn’t know for years how valuable his wartime work was. More details only emerged in 2008 when I asked him to speak to some of my primary seven pupils about his experiences.

“I was teaching the children how to gather impartial evidence from people who had lived or witnessed historical events.

“However, dad told me he wouldn’t have had much to say about the war except he went to work at Bletchley Park in a suit and carried a briefcase every day and he’d been drafted into it after solving a crossword. The talk to pupils never happened.”

Mum Jane did not recognise the significance of John’s brief words until she went to see new film, The Imitation Game.

“It was only when I watched the film with my husband, Blair, last week that the final pieces of the jigsaw fell into place and we truly

realised dad’s contribution to the war,” she adds.

“No one would ever have known or guessed his part in the Alan Turing story because dad was never one to boast or push himself forward.

“This was so typical of him and his loyalty to his country. Now the story is unfolding, we are prouder than ever of his contribution.”

Jane and her family were thrilled when John was awarded a medal for his code-breaking in 2010.

“It was wonderful for dad to be recognised for his contribution,” Jane said.

One of Jane’s favourite possessions is a photograph she has of her dad completing a crossword while holding her daughter Beth, 21, when she was only four months old.

“His love of puzzles lasted till a few months before his death and dad was as sharp as a tack to the end.”

John spent most of his life working in London as an accountant for the Scottish firm, Thomson McLintock, which evolved into KPMG.

On retiring he returned to his home town of St Andrews with his wife, Morag, an artist.

He also loved golf, at one time playing off a handicap of scratch, and was a member of the Royal and Ancient golf club.

The club flag flew at half-mast the day he died and also on the day of his funeral.

Like many of his generation John was a man who never basked in the glory of his wartime effort but moved on quietly with his life when the job was done.

“To work with Alan Turing must have been hugely stressful, but the project must have been ultimately rewarding,” Jane added.