Thanks to Gormangenealogy for that. That information is in an appendix in the Dublin in Rebellion book I mentioned, on page 406. I hadn't noticed it before and it's not in the index, so thanks for pointing it out. It is very odd that these people were allowed to join the British Army or RAF with their IRA records, but I suppose circumstances change and Irish Republicans were always a mixture of different people with different politics, ranging from Communist to Fascist.