The growing strength of the Tory right and the anti-austerity left suggests our stable, predictable system of party politics may be coming to an end.
For 80 years, our system has accommodated large, conglomerated parties of the centre-right and centre-left, a small liberal party and assorted nationalists and unionists. This settlement has proved remarkably resilient in seeing off pretenders before, most notably the Social Democratic Party in the early 1980s, but the edges are now starting to atrophy, leading to fractiousness and fragmentation.
It starts at the edges but it really affects the centre, with powerful disintegrative forces pulling the two main parties towards the extremes, with centrists in both parties clinging on for dear life. As the Tories leach support to UKIP, Cameron moves rightwards to counter their advance.
Labour meanwhile, faces a different challenge. It doesn’t have to counter an exogenous threat; recent events focusing on Unite’s modus operandi in parliamentary selection battles shows its problems are closer to home. The duty of trade unions to represent their members’ interests sees most reject austerity. This will become increasingly at variance with Labour’s more pragmatic approach as the party begins the process of staking a claim to the centre-ground and detailing its plans around deficit reduction and governing a radically downsized state.