At the 2009 European elections, it was clear for any who wanted to see it that the main parties had taken their core voters too much for granted. Nigel Farage’s UK Independence Party tore into the south, and the all but openly neo-Nazi British National Party took two seats in the north (as did UKIP).
But the main parties didn’t see the deluge coming. Their MPs and advisers had been born and bred under the two-party system: it being all they knew, it was all they saw.