But in a bittersweet discovery, he found out he had a brother - who remarkably had been living just a stone's throw away from his home in Blackpool, Lancashire.
The revelation came about after he appeared on ITV's Long Lost Family.
The programme brought the pair together in a pub where for the first time, Mr Belshaw met his half-brother Rob Hall.
In an emotional reunion, airing on ITV later this month, the brothers embraced before talking face to face for the first time.
Presenter Davina McCall caused Mr Belshaw to break down in tears after she produced a photograph of his mother - a woman he had never seen before.
She stunned him by saying: "Do you know where we got it? You have a half-brother called Rob."
And there was a further shock when he was told the 49-year-old had also been living in Blackpool the whole time.
Following a tear-jerking meeting, Mr Belshaw said: "To have a little brother... I never saw this in my wildest dreams. Meeting Rob has allowed me to feel closer to my birth mother.
"He has got so many memories to share. All that will help to build a much clearer picture of the kind of person she was.'
The Mirror reported Mr Belshaw said: "To have lost her boyfriend, the father of her child, I can only see her world fall apart. It's unusual to advertise your unborn child but I think it's an extraordinarily loving thing to do.
"And knowing she had gone to all that trouble to find the most suitable parents speaks volumes about her character. If I had one chance, it would be to say 'thank you'."
Mr Belshaw heard how his mother Frances, who worked in a sweet factory, but would often mention him to his brother. He said: "To know that makes me enormously happy."
After being told of his mother's newspaper advert for the first time, Mr Hall said: "That's heartbreaking." And he added after the tearful meeting with Mr Belshaw: "I hope we will be friends as well as brothers. I think we will be."