Looking at a published tree and checking records,
Honor died in Dublin 1943.
Charles Frost died 1945, Dublin.
They were hospital deaths so no next of kin shown though and different addresses.
The tree shows a death for Margaret Frost in 1985, Middlesex.
I haven’t been able to check that. Did she marry again?
I can’t see a birth for Sean Nolan 1923-1927 but he may have been registered as John.
Was Sean known by half siblings or mentioned in an obituary?