I think you're wearing rose tinted glasses. You say "are becoming" but do you have real evidence that the past was a utopia of rationality where propaganda fell on deaf ears, nobody was ever scared of any threats and everyone loved deeply religious immigrants?
Because the UK I know from my history readings has things like the cold war, the Falklands war, massive tribal struggles between political left and right, and if you go back to Orwell's time you find he found it tough to get published because the idea that Stalin was a bad guy was deemed terribly gauche.
The UK has not had any truly evil governments for a very long time (perhaps, if we judge them by the standards of their day, the answer might be that it's never had an unusually evil government). It's not like Germany where they're super sensitive about privacy and democracy thanks to their experiences the Nazis and then the communists. So not very surprisingly, British people tend to be very trusting of their governments as they never saw how bad things can really get. See: popular support for Cameron executing a British citizen by drone strike, merely because he was in Syria and GCHQ promised cross-our-hearts-and-hope-to-die that he was a Bad Guy™.
This lack of experience doesn't excuse things, mind you .... just explain them. British people (like me) should look to the experiences of other countries to learn from their mistakes and should make sure to avoid them.
But modern UK is not significantly worse than even the recent past where it did things like run a global empire, persecuted gay people, had no minimum wage, etc. And Cameron, for all his faults, has actually been a pretty centrist PM (for a Tory). Certainly more than his backbenches would like.