This was 50 years after partition.
I know the "old" IRA had made attacks on the English before 1972, but, having attained partition in 1921, it was only the Catholics in the north who were still fighting.
My point was that not all that many Catholics were inclined to fight, until the British attacked a peaceful, righteous rally, and then tried to blame the victims. It caused massive anger amongst a lot of people, and active recruiting persisted for many years afterwards.
There's an Irish writer, Adrian McKinty, who now lives in St Kilda, whose series of books are about a Catholic policeman in the Northern Irish police in the 70's and the massive tightropes he has to walk. His protagonist tells of how he nearly joined after ■■■■■■ Sunday but was talked out of it by a man who later became a major IRA operative. I'm not using that as evidence but a lot of different sources.
We used to go down to Molly Blooms in Port Melbourne and quaff Guinness most Saturdays in the early 90's and listen to Celtic City Sons. Their songs were not pro-British.