"The grouping of people together and according them status within society according to the groups they belong to, is as old as society itself."
That is from the Hewett site we look at later.
"GROUP A -
Professional Workers (lawyers, doctors etc.), Scientists, Managers of large scale organisations.
GROUP B -
Shopkeepers, Farmers, Teachers, White-Collar workers.
GROUP C -
1. Skilled Manual (i.e. hand) workers - high grade e.g. Master Builders, Carpenters, Shop Assistants, Nurses.
2. Skilled Manual - low grade e.g. electricians, plumbers.
GROUP D -
Semi-Skilled Manual e.g. bus drivers, lorry drivers, fitters.
GROUP E -
Unskilled Manual e.g. general labourers, barmen, porters."