Roffa:
So NFR, when I'm vectoring to the ILS at LHR with traffic at 4,000ft and I say "turn right heading 240 degrees, cleared ILS approach 27R" can you guarantee me that the traffic won't then descend to 2,500ft which is the stated start altitude on the approach plate for a radar vectored ILS/DME approach to 27R.
Yep, I sure can. Don't say cleared ILS if you don't want them to descend. Did it a heap of times every day during my last stint in APP, due to high terrain and CTA steps.
If they are maintaining/descending to a level "Turn left heading 240, intercept the localizer." Done. No further descent issued. No approach clearance.
Then when clear of traffic/terrain/whatever "Descend to 2500, cleard ILS approach".
That's how I would do and have done it. I'm not saying what you are doing is wrong, but again for standardization with ICAO and not to baby the pilots the questions are being asked. And why is this problem unique to the UK as far as we can see on this thread?
Just interested that's all - no finger pointing.
Cheers,
NFR.