To me, consensus seems to be the process of abandoning all beliefs, principles, values and policies. So it is something in which no one believes and to which no one objects. Margaret Thatcher
There are still people in my party who believe in consensus politics. I regard them as Quislings, as traitors... I mean it. Margaret ThatcherAbove from Margaret Thatcher Quotes - BrainyQuote
Really, while the political process inevitably involves negotiation and compromise--at one time referred to as "The American System"--the idea that the "opposition party" should go along with the "party in power" is poisonous.
This is the one I was actually looking for, though:
In my lifetime all our problems have come from mainland Europe and all the solutions have come from the English-speaking nations across the world.Margaret Thatcher - Wikiquote
Speech to Scottish Tories in 1999