Answers from a sometime IT educator ...
"These include asking whether computing is a real discipline in the same way that maths, physics or chemistry are."
No. Computing is more like plumbing or auto mechanics.
"Other questions include:
" Is programming still a fundamental literacy for the modern age?"
It never was, any more than people understand the processes that allow them to fire up their car and drive off to the shops.
" What is the purpose of ICT or computing classes in school?"
At the grade school level? It has nothing to do with the kids, and everything to do with petty politics amongst the adults in charge.
" Are existing qualifications fit for purpose?"
No, for the simple reason that said "qualifications" were speced out by the unqualified.
" Should computing even be taught in the school environment - do kids learn more outside the classroom?"
IMO, anything more than basic keyboard skills should be outside the scope of grade schools. Yes, allow simple programming languages (I'm talking Lisp or Smalltalk, not that abomination BASIC) and/or bare-bones "how it works" electives for those interested. But this shouldn't be a requirement, any more than autoshop or woodworking.
" Why do students study computing?"
They don't. They study "using consumer goods, and how to get their parents to purchase them for them".
" How much variety is there between different schools?"
Stupid question, How much variety is there between people?
" Do computing qualifications carry as much weight with universities as, say, maths qualifications?"
Not at any decent accredited school that I'm aware of (I have taught IT at several of California's State and UC campuses, and at many highschools & all of the Junior Colleges in the greater Bay Area).
" Is it a problem of perception?"
Probably ... The folks asking the questions aren't equipped to properly perceive the reality of the situation ... figuring out "why" is most likely a better place to spend the money on an 18-month probe.
" Is this problem unique to the UK or could we learn from other countries?"
Its world-wide, in my estimation.