Thank you, Hallmark and Kiwi Jennie. There is a lot to process.
Attached is a Jpeg of my great grandfather's internment date in 1920. He was 43 years old when he passed. When I discovered this, I was able to deduce that 1877 was his birth year. When I then learned earlier this week that there was a Virginia in Ireland, I found a Thomas Hall born in Cavan in 1877 in the Knocknaveagh hamlet near Virginia. That seems to add up. And the rumour he was an "American from Virginia" now seems to have been debunked.
One question I have is can I trust the LDS Family Search site with the accuracy of their information? This was the site I first stumbled on and that said Thomas Hall was born on April 24th, 1877. (Maria Hall seems to have been the same age. Perhaps they were twins or Irish twins?)
I am told my great grandmother worked as housekeeper at her local diocese. This probably meant she was a Roman Catholic. However, their three sons were named: Thomas, George, and John (my Grandfather), first names that fit with the male offspring name of the William Hall line from Knocknaveagh. I suppose it is possible Thomas Hall did not take his Church of Ireland associations with him to Liverpool and was content to have his children raised Catholics. (I know from my Irish history that the Ne Temere decreee from Rome has been a seismic issue for Protestant in Ireland. My late father was from Shandon district of Cork, so I am familiar with that dynamic.)
I will try to get my great grandparent marriage certificate from the Liverpool authorities. I can only assume there were married in Liverpool in the early 1900s. This should show Thomas Hall's place of birth. If it is Cavan, then that should seal it. Although I am not sure how to square the existence of the said Thomas Hall aged 8, who passed in 1885. Who were his parents? There seems to be a lot of Halls in that part of Ireland. I feel like I need to lay all the Halls from that era on to the kitchen table for clarity.
I do not have an account with this Ancestry organisation? Maybe I should get one. If it worthwhile?