Hi Sue,
I have today received the birth certificate for Joseph, as well as his marriage certificate.
It certainly seems like we are on the right track. Birth cert details;-

Joseph Corkhill
Born 18 April 1883--Father=Thomas Corkhill, coal miner. Mother=Jane Corkhill formerly Graham. Address= Manns(?) Court, George Street, Whitehaven.

Marriage cert details;-

Tynemouth Registry Office 14 Feb 1906.

Joseph Corkhill (22), coal miner, 14 Wanless Street Wallsend.
Father= Thomas Corkhill, coal miner.
(who was marrying)
Mary Kilpatrick, (20) 21 Wanless Street Wallsend.
Father= Robert Kilpatrick (deceased).

I have tried to email the certificates to you but keep getting a message to say they are too big.
If you really need to view them, I will have to use another method.

In the case of Joseph's father, Thomas, it seems that he may have remarried for one reason or another because in the 1901 census, his wife is shown as Mary Ann. Living with Thomas' family are a step son and step daughter aged 13 and 11. Their surnames are given as McLaughlin, suggesting that this was the previous name of Mary Ann, although I doubt if this information is helpful in this matter.

I look forward to hearing from you, thank you.

Tony