I can't account for the absence of baby John's name in 1841, as he was born the year before. I suppose it is possible that he may not have been in the house on the day the census was taken...maybe he was in hospital..who knows? In 1866 he married Elizabeth Yorke.
I do not have a copy of the marriage certificate of W. H. and Mary Cooper, but Ancestry has details, and source information, so I have no reason not to believe that Thomas Tilley was not his father, also that his mother- I now believe- was Elizabeth Austin, and not Brey.
It is Ancestry which states that Thomas died in Dalston, Cumberland, but it must be Dalston Middlesex.
I have discovered in my searches that the London Tilleys moved around a lot, as I have several different addresses for them over the years, which could explain why some of them don't seem to exist where I expect them to be.
You are right about my more recent family, and yes, my father did die in Taunton in 1988...I was there at the time.
I am sure you are right about the two Elizabeths being mixed up (like me!) and the Leicester connection must be forgotten by me, so I have thrown away a fair amount of paperwork concerning it.
The Tilley saga is continuing, and there is more investigating to do as I want to go back as far as I can. Thank you all for your interest and help, which is really appreciated.