Hi David I,
The GRO for George William Parkin is: 1859 Sept qtr. Wortley..no mmn.
Henry Parkin I believe died in 1857 June qtr age 35 Wortley.
If this is correct, then George Brown was more likely to be George Wm. Parkin's father.

HAPPY HUNTING:sleuth_or_spy:

"There is a John Edwin Parkin born Q4 1854 Wortley MMN Parkin*.

Here is his death
PARKIN, JOHN EDWIN 2
GRO Reference: 1856 D Quarter in WORTLEY Volume 09C Page 117.

I suspect that the John Parkin age 15 in 1871 was actually

PARKIN, HENRY REDFEARN
GRO Reference: 1856 M Quarter in WORTLEY AND PENISTONE Volume 09C Page 179

He was son of Henry and Ann (nee Redfearn). He would have been stepson not son in law

Dave