British Political Polarization?

How would be possible so that the British political scene be polarized? I mean so that political assassinations do happen, Britain split into Left-Wing and Right-Wing camps (maybe a third camp, such as Communism for example), governments lasting maybe months or a few weeks, like that. In a sense, so that Britain is unstable.

POD is after 1945 but before 1990.
 
It's quite simple, have Michal Foot and Tony Benn take control of the Labour party in the early 70s. It will all go to hell very quickly.
 
It's quite simple, have Michal Foot and Tony Benn take control of the Labour party in the early 70s. It will all go to hell very quickly.

That would polarize the left into two different left wing camps. Brilliant.

But would it destablize the country?
 
It's quite simple, have Michal Foot and Tony Benn take control of the Labour party in the early 70s. It will all go to hell very quickly.

Benn and Foot were very, very different brands of Labour leftism. Have a read of Heppell's 'Choosing the Labour Leader' or indeed Benn's diaries to find out how they interacted and differed.
 
Even without requiring John McDonnell and John Redwood as leaders, the UK is already pretty polarised. A large majority of seats at the last election were considered 'safe', and less than 100 were considered Labour-Tory marginals. It's going to be pretty tough for either to win a large majority with such a small amount of seats available.
 
Even without requiring John McDonnell and John Redwood as leaders, the UK is already pretty polarised. A large majority of seats at the last election were considered 'safe', and less than 100 were considered Labour-Tory marginals. It's going to be pretty tough for either to win a large majority with such a small amount of seats available.
I think the correct word I wanted to use is radicalized. Although polarization is a part of it, just not as much.
 
So any ideas on how to bring about the scenario?

Short of big world events like wars, it's hard to make this happen because the entrenchment of the establishment and historic British stability. The civil service would knock the stuffing out of hardline governments that tried to repeal each other and so on. The divide is more likely to be geographical than political anyway, with North vs South (with London itself divided) being the obvious outcome rather than people in Kent being Thatcherite with Bennite neighbours.
 
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