It's a great irony of British life that the working classes have more disposable income than the middle classes. The government insist that we are all middle class now, they say this to keep working class people happy and assure them that things are better than they really are. In reality, anyone selling luxury or superfluous goods like double glazing, conservatories, window blinds etc will do more trade in a working class area, this is because midddle class people are struggling to pay the mortgage.
There is no different in job, payscale or income between middle class and working class, although a higher proportion of working class people benefit from the social security handout system. There never has been a difference, historically your class was discernable only by a bowler hat and a BBC accent.
However the class threshold, despite the fuzzyness of boundaries, is not one that is easy to cross as mostly it relies in residual self image, and in the image others have upon you.
It's easy to convince many working class people that they are middle class, because they've very little comprehension of the morals, standards, and ways of what middle class people deem to be middle class. Middle class people on the other hand would vehemently object to a vast proportion of the society being recognised in their same social group.
The biggest problem we Brits have is that we tend to view the middle class as 'above' the working class, when in actual fact this is not the case. The two exist in parallel.
Fundamentally the difference between the classes is that attitude, a middle class person would host a dinner party and drive down the road in a slightly aged Rover when at the same time a working class person would scream at the 5 kids whilst driving down the road in this years Renault Espace, paid partly by tax credits, and even when both wear shell suits, the working class person doesn't seem to make it look quite as smart.
To the working class person the Rover is a target, to the middle class person the Espace is a threat.