I did not know that and, trust me, I thought I’d read most of the books on the subject. I must do a bit of research on this as I’m genuinely gobsmacked.
One of the best books on the subject is by Dave Douglass, former NUM leader turned author. His book ‘Red Banner, Green Rosette’ is essentially about the influence of the Irish on Labour and Trade Union development in the North East. It’s got a couple of interesting chapters on how the Anglo Irish conflict impacted on that development. For example why Irish Republicans appeared on Miners Lodge banners and why it wasn’t until the 1970s until Labour Party candidates changed to Red Rosettes from the more traditional (in North East circles) Green Rosettes.