Seriously Martin you haven't a clue what you are talking about, in all my many years living here I have never heard an IRA man/woman or Sinn Fein member mention William of Orange, plenty of loyalist protestants have, but not nationalists. William of Orange was a Dutch invader who took the English throne, mostly without firing a shot, a successful Dutch invasion of England. Yes its about protestant superiority over Catholics, but nothing to do with British oppression in Ireland, that is a totally different thing.
I am no apologist for any violence but I can understand what fuelled the Civil rights marches and it was Bloody Sunday that was the single biggest IRA recruiter, British troops running rampant murdering civilians. Sure they were just scum paddies what does it matter ? Each one of those murderers should be tried and the keys thrown away, one of the darkest days in British army history, and the major event that gave the IRA and other Nationalists the fuel to run their campaigns - hatred of Britain, British governments and the security forces.
Its fair comment that most modern paramilitaries on both sides are gangsters but back in the 60s and before, nope their view is they are/were freedom fighters (or community protectors if protestant) and the British ruling classes most certainly oppressed the indigenous people here, both protestant and catholic, as they did in Scotland and Wales.
And regarding the London attack politics does not fuel that sort of thing but Wahabiest theology which comes from Saudi Arabia. Maybe its time the UK stopped supporting Saudi Arabia.
I am pulling out of this now before I say something I might regret saying.