:-) Super to have the photos.
Family history can be a long, time consuming and often expensive process, it really is best to find out as much as you can about one generation before moving on to the previous one. The info we find for each generation helps us as we go back.
Asking questions is good and everyone is willing to help but we try to help by by offering suggestions and showing you the different ways you can use to sort out who did what and when. From there you can get the records and decide if they are the correct ones.
I never say that anything I find is 'definite' but offer possible theories. It wasn't a case of me saying I was right and you saying I wasn't, I offered a theory to be explored.
The electoral rolls were another avenue to explore to narrow down of William Spence's year of death to make the 'possible' death registration that Candleflame gave you of Q2 1953 more likely. Certs are expensive and we all want to be as sure as we can be before spending out on one. If those electoral rolls were a match for the family (which seemed highly possible) they indicated that he was still alive in 1931 so that increased the likelihood of the death reg which was a match for name, area and age.
IF you are in Tyneside the area I'd suggest going to Tyne and Wear Archives, they have parish registers on microfilm which you can explore to see if he was buried in a churchyard, though if he died in 1953 I'd also be looking at the civil cemeteries of Gateshead East and Saltwell (both on microfilm at Tyne and Wear Archives)
Another option is to go to Newcastle Library and look at the microfilms of the Newcastle Evening Chronicle to see if there was a death announcement in the newspaper, they often give details of where the burial took place. Means looking through all the editions for 3 months covering the June quarter of 1953, which is time consuming but free. Other than that you need to buy the death cert to see if its the right one.
As for the WW1 service of both John and Robert William, though you couldn't find a service record that is not unusual as about 60% of the WWI service records were destroyed in WW2 when the building they were stored in was hit with an incendiary bomb. The ones that weren't burned were damaged by the water they used to put the fire out, so its hit and miss to find a surviving record. Also bear in mind that though your Dad says his Grandad never mentioned serving in WW1, many men did not talk about their service, they were ordinary lads who went through an extraordinary and horrific experience and its no wonder many didn't talk about it afterwards.
I am sorry, but the rules of the forum are that we are not allowed to do look ups on the 1939 Register for copyright reasons. Even if you don't have a subscription to FindMyPast, you can try a free search of the 1939 Register to see if there are any possibles so try a free search for William and Ann to see if there are any possible results.
To go further back you would, as has been suggested, need to buy the marriage cert for William Spence and Ann Alder to see what the names of their fathers were and also their fathers' occupations. Armed with that info you can explore previous census returns to see if you can find them.
Boo