Hello Heathrow Director,
Whether pilots like it or not is a total irrelevance.
It's not irrelevant, HD. It would be if we weren't able to motivate WHY we didn't like it.
At this time, that's the way it's done in the UK, so -sadly- we have to follow the existing procedure. That doesn't mean that there would not be room for improvement. And if it can be improved, it should. Over the past years you're defending this phraseology with such an obstinacy that
I'm starting to believe that you might have invented and introduced it! 
It's unambiguous...
No, it's not. Even if
I do realise that it I shouldn't start following the G/S when cleared for the LOC only, it's clear from others posts in threads about the same subject that there are several people who still would start following the G/S when they hit it. Why? Because 99 times out of 100 that's what a controller will let you do. So, I'm not amazed that someone would start descending on the G/S when they can't get through to obtain a clearance due to ATC freq congestion for instance. If, on the other hand, "cleared for the loc" would be a clearance not routinely issued, then people would probably pay more attention to it and realise that there is a good reason not to leave the current altitude! Also, when you clear traffic for the ils when he's LOC established, what's stopping him to not to think he might be allowed to descent immediately to the published alt?
No, it's not. Reread my previous paragraph for a first reason. It's not unambiguous, so it's not safe. Then (re)read the click-able links in my
post nr 10 for some more reasons why it might be unsafe. Having to intercept the G/S from above was mentioned as one of the Swiss cheese holes lining up in the Turkish crash in Amsterdam. Notdavegorman explains in
this post why getting a late descent clearance increases the workload. If a certain phraseology sometimes unnecessarily increases the workload, that is already enough reason to at least reconsider improving the procedure.
If I have to believe you, traffic congestion never occurs on LHR ATC freq. Even if I haven't been to LHR in the last 10 years, I find that hard to believe! Or is LHR APP freq really that much calmer then BRU, FRA, MUC, AMS or CDG? Unnecessarily increasing an already busy freq can't be enhancing safety, now can it?
So, here's my suggestion:
Let's suppose the traffic is on an intercept radar heading for the LOC...
case 1: he's already at minimum G/S intercept alt: simple say "Cleared for the ILS"
case 2: He's still above the published altitude but ATCO has no objection for descent to the published alt: say: "(optimally:cleared for descent alt XXX and) cleared for the ils"
Case 3: You want the traffic to maintain the higher then published altitude until G/S intercept:say: "cleared for the ils, intercept G/S at XXX (current alt)"
All these cases require just 2 calls (clearance + readback) iso 5! (LOC instruction + readback + established on LOC + "cleared ILS" + readback)
If you really want the traffic not to descend, not even when he hits the G/S then and then only would I suggest you to use "Cleared for the LOC only, maintain XXX alt until advised"
That is the way it's being done in most parts of the world I fly to and is in my opining shorter safer and less ambiguous then in the UK.
So, please, if you reply, which I hope you do, don't just come back to say " That's how we do it over here and it's safe. Just live with it!" but try to explain the
reasons why you think the UK way is safer, less ambiguous and easier!
Respectfully,
Sabenaboy