The UK Cabinet Papers for 1974 have been released - this interesting year contained the aftermath of the Yom Kippur war, a miners strike which brought down the Heath government and the collapse of the Sunningdale power sharing agreement in Northern Ireland.
A summary of the latter is here - unfortunately only fragments of documents have been scanned - and I'm a long way from Kew to look at the originals. Some sort of public domain online archive of such documents would be very useful - I wonder if governments (who generally hold the copyrights, except in the USA) would cooperate.
The document summaries are still quite interesting - had the agreement succeeded, the Northern Irish troubles would probably have ended over 20 years earlier. It's hard to see how the then government could have stopped the (almost entirely Protestant) power industry workforce from striking - short of conscripting them into the army and forcing them back to work more or less at gunpoint.