Rustle,
No, my question wasn't tongue in cheeck actually!
LHR may only be the 15th busiest airport in the world, but none of the others mentioned share their TMA with Gatwick, Luton, Standstead
and City! Although I don't know for sure, it wouldn't surprise me if the airspace really was close to being full.
I don't think there's an issue with the actual airways. As others have pointed out, the average PPL going for a £100 hamburger in his PA28 will not be at the same leves as PA28s. But arriving and departing heavy jets on SIDs/STARs
will be at the same level as the average PA28, and I'd guess that trying to vector all us guys around the heavies, in IMC, in a TMA which already serves 5 international airports, would be a complete nightmare. And our weather means that pilots will invariably be in IMC more often than they would be at many of the airports slim_slag has listed.
I may be completely off the mark here, I don't know. But it was a genuine question
FFF
-------------