A Wallis Darlington and Matilda Adams married in Dublin in 1908. By 1911, they were in Tyrconnell Street, Dublin with a daughter, Charlotte. Religion noted as Church of Ireland. Matilda from Limerick. A Charlotte Darlington, aged 1yr also died in Dublin in 1911.
Wallis, birth year 1884, is potentially the chap of same name/age who died in Dublin in 1945 (perhaps a reason for Rupert/John returning to Dublin?).
A Matilda Darlington, of same approx age as the 1911 census Matilda, died in Dublin in 1957.
Who were Matilda and Patrick Walsh? Were Ruth and Rupert baptised with the Walsh surname?
They were baptised in Dublin on 10 January 1917 and parents were named as Matilda and Patrick Walsh. Address on birth and baptism certs was 53 Great Orford Street, Liverpool. Baptism was in a Protestant church
Could Rupert/John have used the Walsh surname?
Have you ruled out the John Derwin marriage in Dublin in 1949?