Many thanks for that Carole, my, you work quick and there is some new info for me so very much appreciated

Yes it appears that Norah came with her husband from Devon to South Wales, her husband died in a railway accident in 1872 and then Norah is with William on the 1881 census. No marriage, lots of children (including stepson), then William disappears again

. (after he dies, Norah does re-marry again to a Tuggwell I think)
If William was born 1820-31 in Worcester then between this time and 1873 (the birth of first child with Norah) he also made his way to South Wales. I can find absolutely nothing on him for this period

William's death cert says - 17 Nov 1894 William Charles Williams , Gardener of Rumney at age 74 as you rightly say, so I am as sure as I can be that it is him. So maybe his headstone, if there is one, may give a hint or a clue that I so desperately need?