Long Lost Family announced the heartbreaking death of the person who found Simon Jeffrey when he was abandoned as a baby.
Simon had been abandoned in a wooden corned beef box in the ladies toilets of the Railway Tavern pub in Greenhithe, Kent in October 1963.
He appeared on the special episode of the ITV series tonight as he tried to track down his family, despite being born with no identifying features or details.
Tonight, Simon read a newspaper clipping which revealed that a woman called Mavis Gordon had found him in the toilets.
But after the episode aired this evening, an ITV announcer confirmed the sad news that she had died since filming.
She said: "Sadly, since filming, Mavis Gordon who found Simon Jeffrey as a baby has passed away.
"Our thoughts are with her family."
Viewers were left in floods of tears as an Simon was finally reunited with his four full siblings this evening.
Simon was taken in by Gravesend foster carers Cathleen and Earnest Jeffrey, who went on to adopt him, but had no idea how agonisingly close his path would cross with his biological family throughout his life.
In the new ground-breaking documentary series, presented by Davina McCall and Nicky Campbell, the team behind Long Lost Family managed to find where he came from.
When Simon first took A DNA test two years ago there were matches, but none were close enough to identify his birth family.
But they managed to find a full sibling, which opened the door to a whole family for Simon.
Simon had six older siblings, but sadly two brothers and both his parents have passed away.
Staggeringly, they all grew up in Gravesend, just two miles from Simon's house, and could easily have walked past him in the street.
Three of the siblings, Tony, Julie and Christie, agreed to meet up with Nicky and explain they had no idea they had a secret younger brother.
"It's quite sad that Simon has found us now without mum and dad being around," admits Christine.
"He's our little baby brother and hopefully we will be one happy family."
And fans were in bits, with one tweeting: "Blubbering wreck watching #LongLostFamily so happy Simon found his siblings!"
While another commented: "My heart is breaking for Simon. He has such abandonment issues that he was genuinely surprised to hear his siblings wanted to meet him. We’ll never know why his married parents abandoned him & kept his siblings... but I hope his siblings shower him with love #LongLostFamily."
A third wrote: "I think Simon’s reaction to @ThisisDavina delivering the news is possibly the loveliest I’ve seen on #LongLostFamily or #BornWithoutTrace."
"What a lovely man Simon seems, can't imagine finding out you were abandoned, let alone abandoned and having six elder siblings who were kept. #LongLostFamily," another wrote.
*Long Lost Family: Born Without A Trace is available on ITV Player