Aah, so you do agree
that's a start, I suppose.
I don't think the UK state has ever attempted to categorise class in purely Marxist terms but, just to play along with your line for a moment, if that were the case, there doesn't seem to be any question relating to ownership of the means of production.
In which case, for a state that you say is so concerned to ameliorate discrimination, it seems something of an oversight not to ask respondents to self describe their class as is done for the other innate and acquired characteristics in questions 14. 15. 16 & 27.
e2a :