Well the only constant I can see is the Conservatives. First you had Whigs, then Labour, then Lib Dems and Labour. At current Labour's main problem is the lack of focus. For 75% of the last century you had the Socialist Vs Capitalist, and the focus on the "Working man."
Well now the down trodden masses have been lifted and no longer oppressed. That leaves Labour with no voter base.
It is interesting how the Tories have morphed though. Most of the Uplift for the population was from them, and that was likely in the interests of maintaining power. Much Like what happened with UKIP eroding their position, eventually it became to great to resist and the Referendum was granted. I think we're seeing the Tories morph again into a Centre Slightly Right party. But that leaves the Lib Dems and Labour an amorphous squishy mass that needs to be reformed again. Perchance its a parasite, it needs to latch onto some cause to give it form. At the moment its flailing around searching for that form. The Benefit class is a non-starter, The Minority classes is also a non-starter, which leaves...?