It would appear that the new definition of middle class is if you have a drive and/or a garage. Yet I know a great many people that work on the shop floor, builders, plumbers, electricians, farm workers - the list can go on - that have drives and garages. It all seems a bit muddy to me (coming from a family of miners and farm labourers).
Aren't plumbers and many trades now the new middle class? There's a road between Lancaster and Morecambe with decent sized, semi detached houses with gardens and garages. There's similar on the A6 through Bolton le sands. Once they had just normal family cars like Sierra/Mondeo size often better brands. Now they have them plus their trade van or two.
A work colleague had a son who was a plumber. His son did a few years working a few weeks at a time in London with only the odd weekend off. He worked hard and came back with a nice wedge that he used buy an old farmhouse with a bit of land, not to work? All without be big mortgage. He could have worked longer down there but he'd git enough for his needs so he went for the standard of living up this way.
I only mention that because I know a guy who did the university degree, technical job that evolved into management. A lot of responsibility for multi million pound IT infrastructure development. He worked out that he could get more money by becoming a plumber. If class is about value then traditional professional roles and traditional trades could have switched classes.
Btw I come from chartered engineer and office manager stock. Uni educated and expected to head to chartered engineer status too. I'm now a highly educated dogs body. Well not quite I'm a QE but there's a certain truth in my having gone the wrong way in class system, a middle class bred but working class living. It's certainly very muddy now.