The Mary Berry Story returned for part two on Friday night and the Bake Off judge shared a tragic story leaving viewers in tears.
Discussing her family life, Mary revealed the story of her son William, who died when he was 19.
She recalled how William had returned home for a family meal and borrowed the car when he was involved in an accident.
Lots of viewers were left in tears by the revelation.
Mary said: "We had a nice family meal and then on Saturday he asked if he could borrow the car.
"It was a glorious January day and it was sort of 1 o'clock and he wasn't home.
"The door bell rang and there was a police man there and immediately then I knew why. He said there's been an accident and I'm sorry to say your son is dead."
Mary said her son "looked so beautiful and so lovely" when she saw his body at the hospital.
"It was nice to say farewell," she added.
Many viewers were unaware of her devastating loss.
Mary then paid a moving tribute to her son and said her husband - Paul - became extremely important after William's death.
"We had him for 19 years and he was such fun and we have great great memories.
"I didn't want to work in London after that because I didn't want to leave Paul. It was a great comfort to have each other - your life long partner. I was so lucky to have him."