Any Brits hanging out here on FR that can characterize that area and the people who live there?
I thing the dropping of the words "Irish Republicanism" was purely a sop (probably by Reuters) to the PC crowd.
Yeah, Reuters sure wouldn't want anyone to suppose that "Irish Democrats" like Ted Kennedy were involved, would they? :-)
Croydon is a fairly large area of South London suburb. As such, is hard to put in any particular category.
I think you can assume that the people arrested are Islamic, the 'ruling out' of Irish Republicans seems to leave that as the only realistic alternative.
Of the places named, Wolverhampton has an especially large Islamic community.