You may want to try for James' birth certificate.
There is a James Gelling born in the March quarter of 1902 in Barrow-in-Furness, volume 8e page 801.
A James Gelling born in Barrow the same year and with the same father's first name would put him in the probables column.
The only other Gelling family that I could find in Barrow in 1901 was that of a widow, Frances Gelling, and her thee young sons. who was living with her mother, Jane Wilson.
Her Husband's name was William Gelling.

Also I think that this William and John were brothers as they were with their mother Eliza Gelling (widow, age 59, b. in Ireland) in the 1881 census.
In 1871 this trio was on the Isle of Man at 77 Quilliams Court, Douglas. Eliza is shown as head but married.
In 1861 it looks as though the family is at No 1 Ct, 9 St Anns Street, Liverpool.
Here we have:
James Gelling 43 shoemaker born Douglas
Eliza 29 born Ireland
James 12 born Liverpool
Catherine 7 born Liverpool
William 3 born Liverpool
Eliza 1 born Liverpool
Finally a bit of mystery: in 1871 at 37 Market Street in Douglas there is a James Gilling, lodger, age 50 shomaker, married but without his family. I do not know how close Quilliams Court is to Market Street.
Hope this helps