Thanks everyone for trying to help -
Anything you see on Ancestry for Ellis Porter is mine as George Nelson Ellis is my grandad, the illegitimate son of Gideon Nelson Billingham and Edith May Ellis b.21/11/1901 reg Q1 Aston 1902 at 9 Miller Street. His birth cert only refers to his mother Edith May. At some stage between birth & 18911, Edith May has left her son with the Foxley family at 47 Miller Street, and his name is being recorded as Nelson Billingham, suggesting that someone knew this story about Gideon Nelson being his father. He used this name through service in WW1, his marriage and the reg. of his first 3 sons (my dad being one). In 1933/34, he had the certificates annotated legally to revert back to his legally registered birth name of Ellis.
Gideon Nelson Billingham, son of Gideon, grandson of Jeremiah, all chain manufacturers in Cradley Heath. Father Gideon died 1899 (I'm awaiting a copy of his will), presumably leaving the business to son Gideon Nelson - the will confirm or deny. At some stage, Gideon N is in partnership with Thomas Grice, but which ceased (notice in London Gazette) in 1902.
There are umpteen Gideon Billinghams, chain manufacturers in Kellys etc, living at various addresses (further complicated by the fact that they're often shown as Mrs G. Billingham) - they are not Gideon Nelson. Gideon who married Amy Wellings/Smith and went to Warrington, is not mine either - this one's father is William. The one who is shown as nelson Billingham d.1951 and in various directories was born in 1895 and was a grocer. We can find no links after 1902. We have every cert you could think of, tracked every similar name - nothing. And as I've said, frustratingly, there is no trace of Edith May Ellis either, in any respect. I've been to Worcester Library and Dudley Archives - found a few docs relating to Jeremiah b.1789 and Gideon b.1822 which were very interesting and gave a good indication of how well off they were.
We have grown up with grandad telling us this story - my dad remembers being called Billingham one day and then going to school as Ellis on the next! - never really knowing if it was the truth. My cousin and 1 had had our DNA tests done by Ancestry and so we recently enlisted the expertise of a professional DNA 'detective'. She has matched us irrefutably with both the Gideon Nelson family and Edith May Ellis family; plus, into the bargain, having been shown a match on Ancestry for a close cousin, we find our grandad had fathered an illegitimate son in 1930 (no one knew!). When we saw the son's photo sent to us by his daughter...we didn't need a dna test to prove the link - he's a carbon copy of all the brothers and sister (his half siblings)! We have met our new half 1st cousin - what a gift!
If anyone does come across anything, we'd obviously be grateful to hear about it. Thank you all again for taking so much time in digging into the records.