The 1891 and 1901 census show that Ernest was born in Freemantle, Hampshire. I think if you look up Ernest BLACKFORD in the 1911 census you might find him boarding in Southampton, Hilda is also living at the same address 
At this time he was a Registrar's Clerk (College Office), working here,
http://www.southampton.ac.uk/about/reputation/history.page
https://en.wikipedia.org/wiki/University_of_Southampton
I think his mother Ann could have died just before the 1911 census,
Ann BLACHFORD Mar Q 1911 Southampton 2c 55
Age: 55
Hope this helps,
Thank you very much and apologies for the slow response.
The pieces are coming together now and it's revealing a very sad story too.