Are nutty parties necessary?

Ultra-ist parties are on the rise across the EU. France had to invent an ersatz populist movement to keep its own demons at bay. 

I'd been reflecting recently that the way the UK has apparently 'contained' its extremes within the traditional two-party system was perhaps admirable and certainly historically very familiar. 

But I am still not sure, and Matthew Parris disagrees... 

"A substantial minority of British voters, to both the right and the left of what we may call the centre, are frankly nuts. 

"They need and deserve nutty parties to vote for. Take the left. It’s a tragedy of our era that voters, activists and a few politicians too who are rank Marxists, not democratic socialists, should have lodged themselves within the Labour party so securely that they now control its leadership." 

He goes on to conclude that a re-surfacing of UKIP, would thus not be such a bad thing, as it would purge the Tory party of some of its own crazies.