I can think of three ways of describing "class".
The Marxist Way:
Those who live off capital are the exploiting class. The rest are working class, whether they work "by hand or by brain". By this definition, Cherie Blair, an extremely rich lawyer, is working class and exploited by my mother who lives off savings earned by my father through a lifetime of hard work. Marxism is, of course, nonsense and has been fully refuted by the Austrian School of economics.
The British way:
Social background is the key. Members of the aristocracy are the upper class. Middle class people wear suits and work in offices, own their own homes, stay at school until aged 18, have professional or academic qualifications and speak grammatically or at least exhibit some of these characteristics. The working class are to be found in factories, rent their homes, don't value education and speak "differently". Using these definitions, Cherie Blair is clearly middle class.
Well, of course it's not quite that simple nowadays. Most people are homeowners, albeit with mortgages. Half of children here in Scotland go on to higher education and when I lived in east London the blokes in the pub wearing jeans were City bankers and the ones in suits worked at the docks. The British definitions of class are now quite meaningless. I propose a "third way".
The libertarian way:
Credit for the idea of libertarian class analysis goes to Franz Oppenheimer. He writes:This libertarian view of class is the only one that makes sense. Those who work in the free market are, well, working class. Those who live through the state - as public sector employees or as welfare recipients - are exploiters. They are the true ruling class and Cherie Blair is at the very pinnacle of that class.
There are two fundamentally opposed means whereby man, requiring sustenance, is impelled to obtain the necessary means for satisfying his desires. These are work and robbery, one's own labor and the forcible appropriation of the labor of others. The State is an organization of the political means. No State, therefore, can come into being until the economic means [private sector] has created a definite number of objects for the satisfaction of needs, which objects may be taken away or appropriated by warlike robbery.