Going around it!
Sam,
FWIW, my experience is every single time when heading east [traveling from Bristol / Gloucester to France / Belgium in the London TMA at 10,000ft] I get vectored way south of Gatwick. My direct route would be over the southern end of the Heathrow TMZ, but I get sent south not even over Gatwick but down to the south coast just about to [or actually to] the SFD VOR before I can turn ENE again on-track.
Heading West from France / Belgium back to Bristol / Gloucs, each time I get vectored where I would like to be [southern end of Heathrow TMZ] and get a great view of Heathrow on the right side if the weather is good.
This is presumably due to 'normal' east/ west routes and heavy iron holding patterns: the above experience is irrelevant to the flight plan filed and accepted route in each direction [which is way different].
May be different at 6,000' of course ..
Tom