As I mentioned... my childhood was very "upper" (affluent) middle class. I know fairly well that it was not "ordinary" middle class. I had class mates that were the latter (parents were teachers as zillionaire says, and no, they did not have our lifestyle). In fact, I was sometimes asked to give a tour of our house (6 bedrooms, living room with dining area, games room, study and so forth) once they saw our neighbourhood.
I guess the problem at hand is that there's a big difference between "upper" middle class and the "ordinary" middle class, and I think it's mainly the ones who belonged to the former that feel the squeeze in particular. Teachers I know now actually have a better lifestyle than the ones from 30 years ago.
However, I think it is very flawed to just brush this under the carpet in the "be lucky with what you have" manner as many here seem to have. In fact, that is dangerous for the UK economy. The company my DH works for (very highly skilled job) admitted bluntly that the workforce with this particular skill level is paid 15-20% less in the UK than in other developed countries. Including other benefits paid, you can say that the UK employee costs about 50% less than in other developed countries.
Basically, in the company's view, in terms of cost, the UK is somewhere between a developed country and an emerging one. They get the infrastructure, stable political system and skill more aligned to a developed country, but pay a lot less for it.
They can do this because everyone else in the UK with this particular skill level doesn't expect to get paid more. You see, they benchmark against what other companies pay, and every single multinational company seems to choose to pay less. In the long-run, this is BAD for the UK. And this whole "be grateful what you have" and "don't expect too much" thing... really isn't helping here.