Rilba’s attempts to investigate the matter were always rebuffed by her mum.

But her daughters, Charlotte and Harriet, bought her an   membership for Christmas in 2018 and she made the “life-changing” discovery.

In a twist of fate, Mary Brand, from Ontario, Canada, had also been searching for long-lost family when she found her English half-sister.

Mrs Brand made multiple attempts to get in contact after Rilba was flagged up as a potential first cousin – but Mrs Jones ignored them believing they were a scam.

Desperate for a response, Mrs Brand asked her daughter to send a last ditch message to see if she’d get a response which prompted Mrs Jones to put her own daughter on the case.

Just a few days later Mrs Jones received a phone call from her daughter Harriet who revealed that “I found your dad”.

Mrs Jones, a retired nurse, from Hull, east Yorkshire, said: “I’ve wondered all my life about my identity and this has been life changing.

“All of sudden Mary’s at my doorstep and I couldn’t have felt more at home.

“It’s better late than never. I couldn’t believe it, I’d been waiting for this moment for over 70 years.

“I was so pleased to learn who my father was – he led such an interesting life and was a war hero.”

Daughters Harriet, 44, and Charlotte, 40, thought the gift could help their mum find answers she’d sought after he whole life.

Harriet said: “When we bought my mum the DNA test I secretly longed for answers about her identity.

“I wanted them for her, because I knew she was troubled by not knowing. Six months after giving the test to her the answers came.”

Rilba was told her father was Flight Lieutenant Blair White, who was shot down and killed in the invasion of Sicily in 1943, when she was just two.

But when she was 14 she was sent into a back bedroom as a punishment where she discovered an account which had been locked away which revealed her mother’s secret pregnancy and subsequent efforts by relatives to find a “suitable” husband.

When she confronted her mum with her new information, she was immediately shut down and they never spoke about it again.

Her real father was Flight Lieutenant Harris, who left Canada to join the RAF in 1937 – and probably met Mrs Jones’ mother when he was being treated for injuries at Torbay Hospital in Torquay in 1939.

Mrs Jones was born in September 1940 – nine months later.

Flight Lieutenant Harris’s plane was shot down in 1942 during a raid on Hamburg and he spent the rest of the war at the Luftwaffe-run camp Stalag Luft III, which held captured Western Allied air force personnel.

In 1943 prisoners constructed a gymnastic vaulting horse to disguise men, tools and containers of soil, while a tunnel was dug, allowing three men to escape to safety.

Mr Harris’s role in the break-out was re-enacted in the 1950 film The Wooden Horse.

After the War he returned to Canada and went on to have four more children. He died in 1964.

In Canada Mrs Brand plans to attend Rilba’s 80th birthday later this year.

She said: “Meeting Rilba was like a wonderful gift from our father. He has been dead for 55 years, but now I have another piece of him. She’s smart – just like our dad.”

The two sisters speak regularly, exchanging emails and stories from their lives, patching together pieces that were once missing.