That was just some new research/BBC survey.
There are various ways of defining/ascribing class, and not all of them overlap neatly. Most are about forming collective perceptions of each other though.
I said it already upthread, but although people's consumer choices are the most visible signs of their social class, I don't think they are really the most important aspect of class. Getting hung up about lawyers popping into Iceland for frozen pies and chips for their tea and checkout assistants buying artisinal cheese and biodynamic wine isn't very productive.
I would disagree with this though:
"I think you need to feel comfortable wherever you fit in within that class structure, aspiring to be something you are not is never going to feel great I wouldn't have thought."
I don't think that discussing class should ever be a way of encouraging people to stay 'in their place'. Personally, I think it's good to have an awareness of how class and power function in society, and where you stand in respect to that power, in order to see exactly what hurdles and barrier you - and others - face in their lives, and think about what action can be taken to overcome them.
On the subject of middle class people insisting that they are working class, I think people often feel that becoming middle class is like suddenly belonging to another distinct category of society. But being middle class is really more like being in the middle of a power dynamic. In the middle of the everyday push and pull of power between working class people and people who control markets and industries. Just because you, personally, have more leverage, doesn't mean you have to switch sides. So I don't see any conflict between having middle class means and working class values.