Parker Bowles herself has two children from her marriage to Andrew Parker Bowles, Laura and Tom.
It turns out that’s the name her grandchildren call her, too.
“I don’t know if it’s because they think I am!

It is funny but is still very sweet.”
Even her great-granddaughter, Lilibet Diana, was named for her.
That jot down of nickname apparently isn’t so unorthodox within the family.

Queen Elizabeth herself called her grandfather King George V “Grandpa England” (via The Mirror).