Thanks everyone so much for your help, it's really opened up my search and solved the mystery of Harry's 'other' mother! I will now check out the James Keeble / Ann Howell marriage certificate and as a James Keeble died in Bosmere district in 1893 that looks likely and explains why Ann was a widow in 1901. He was aged 75 then though so would have been an awful lot older than her!
I had found this Ben Johnson Howell before but discounted him as he married someone other than Ellen / Ann Welham, even though his occupation fits Harry's birth certificate and year of death fits with Harry's father being dead when he married, and it's a pretty unusual name.
Given that Ben was marrying Lydia Wright only 6 months after Harry's birth, and we cant find a Welham / Howell marriage, should I assume that Ben Howell and Ann Welham were never actually married and therefore Harry was illegitimate? Could a woman say she was Ellen Howell nee Welham without having to prove it?
Thanks again,
Charlotte