And how it's being used on here to forecast that the poor high earners will be worse off than anyone else over the next few years?
It's absolutely not true, for one. The worst off will be the worst off.
I grew up in poverty. My kids are middle class. I know the gulf that exists between the two, firsthand, and secondhand from working with kids in inner London for twelve years.
The squeezed middle will be ok. So can we stop pretending that people who earn over £50k a year are on the brink of destitution? It's really demeaning to those who survive on a lot less.