We used to have a good system - after a change of government, either way, the incoming lot spent the first couple of years fixing the mess the others left behind, then a year or two pursuing those policies for which they'd been elected and which were generally a good idea. After that it became dogma-driven, until the electorate got fed up with the resulting mess and switched back again.
Generally the Tories were better at creating wealth, Labour better at distributing it so in the long term it all worked nicely.

At present though, neither side seems up to doing anything useful.