Why devolve the game setting to the Sub-Regional Seats of Government (SRSG)? Well, a couple of reasons. I have to admit that I 'm having trouble rationalising how an armed revolution can be turned into a civil war whilst central government mainatins it's grip on a country the size of the UK. Not without it seeing it being a long and protracted affair.
Pushing the government of the hypothetical crisis out to the regions actually makes the whole thing more realistic - to me at least - and means we can define a specific region as our gaming area of operations to play out the ebb and flow of the revolution and onset of civil war.
I'm not sure how much of the sixties/early seventies national crisis/emergency and war Sub-Regional Seats of Government infrastructure existed in 1979 - Emergency Planning taking over from the defunct Civil Defence in the mid-1970's - but it works for me as an assumption for my games, especially as they were aligned with the local military command District.
For an outstanding work on emergency and war government in the UK see Steve Fox's excellent thesis THE STRUGGLE FOR SURVIVAL: Governing Britain After The Bomb, which is wholly available online. I'm sure you'll find plenty there for your own game setting.
There's a lot of potential within this framework - attacks on the regional centres of governments, local coups, military take-overs, division and civil war at a county or borough council level. Do the local Territorials who are local civilian workers after all, many of whom may be unemployed, follow orders or do they whole or in part declare for the local opposition - shades of the first days of the Spanish Civil War in Madrid and Barcelona?
Any thoughts are welcome.