I never did give up.

I have finally re-opened the mystery and now have the answers. Much of which that was suggested here has proved to be correct.

So, this is the correct information.
William John Taylor Marley was born on the 9th July 1881 in Sunderland, Bishopwearmouth then classed as being part of Durham. This would be the person suggested by rosiemagic. As with the marriage certificate, there is no father named. His mother was Sarah Marley born 1857 in Sunderland. Her parents I believe were Richard Marley and Sarah Wilson.
His birth certificate states his mothers name only as Sarah Marley, but I believe that she may be the same person who appears as Sarah W (Wilson) Marley, but, that is another story.
Sharon was correct with the following:
There is a William Marley in 1901 living at 152 Leadgate. St Ives, Sunderland Durham.
Frank Marley Head 34 coal miner born Sunderland.
Matilda Marley Wife 32 (cannot make out pob)
Caroline Marley dau 6 born Sunderland
William Marley Nephew 20 coal miner born Sunderland
As Kath suggested, the 1911 Census showed the following:
19 Waltons Row, Blackhill, Durham
William Marley, 29 (1882), Coal miner, Sunderland
Mary Hannah Marley, 27 (1884), Blackhill
Leonora Marley, 4 (1907), Blaydon
Norman Marley, 2 (1909), Chopwell
and later they had another son named as Willie Marley.
I believe that his wife, Mary Hannah Marley to be Mary Hannah Sayers. She interestingly had siblings named Leonora, Norman and Willie. As Kath also stated, there is a death registered in 1920 for a Mary H Marley. Norman and Willie are the ones that died in London. Willie has the same birthday as mine although he is a bit older
As with Kath, I have not found a marriage between them, but only the one for a Robert William Marley and Mary Hannah Sayer in 1902.
Thanks to all that have contributed and to Ladyhawk for going through all of the posts and condensing it into something readable and concise.