A grandfather has tragically collapsed at his eight-year-old grandson’s funeral and died, leaving a Sydney family in “unimaginable pain”.

Stan had farewelled little Tommy — who died of cancer earlier this month — at a funeral service last week when he walked out of the chapel and collapsed.

The grandfather was given CPR by doctors and nurses who were attending the funeral and taken to Blacktown Hospital, but sadly died.

Tommy’s mom and Stan’s daughter, Amanda Adams-Bennett, said she was “working through the rollercoaster of grief, anger, sadness and other emotions” on a fundraising page to raise money to support her mother, Lin.

“We had to say goodbye to our son and now my dad,” she wrote.

“My mum lost her loyal husband of 47 years. The most patient, kind, respectful, and honest man I know. I was so proud to call him dad, and our boys their poppy.

“Our family is going through the most unimaginable pain. Two beautiful people we love with all our hearts, gone from this earth far too soon.”

Adams-Bennett told 7News her father “lived for his grandkids”.

“He had such an amazing bond with Thomas … and when he collapsed, I thought at the time he must’ve just been so overcome with grief,” she said.

Tommy was diagnosed with diffuse intrinsic pontine glioma (DIPG) — a rare and aggressive type of childhood cancer — in September last year and died on July 2.

His funeral was on July 12, now also the date of Stan’s death.