Bex,
To be honest, I've seen traffic up at 9 or 10 abeam the field on a night shift but the point of conflict is further east than abeam the field and if it's an opposite direction confliction(GWC-HOLLY versus BEXIL-MID), one would like to see the aircraft at min stack well before the conflict point.
With respect to Scott, he doesn't operate in our TMA (although his view is fully correct, accurate and in accordance with ICAO and Uk procedures).
However when the position (on restating of restrictions) was clarified a few years ago, many of our colleagues felt it would increase congestion on already busy frequencies.
If the restriction is not restated it no longer applies, however pilots can do a great deal in helping the smooth running of the London TMA by doing their best to comply with the restrictions anyway (unless the frequency is very quiet and they can ask specifically)
I really don't want to open this one up again, more info can be found
here
and here