Hi Marilyn,
My father is also searching for a Herbert Thorpe Callister, born November 19th 1903 in Marown, Isle of Man.

He was the son of John James Callister and Mary Emma Thorpe (b.1876).

Herbert's grandmother lived in Greenfield, Yorkshire.

Herbert went missing in his late teens from Ellesmere Port.

From what you've said, your grandfather was born some 20 years earlier...