Capetonian disagree, STN is the last hub yet to be fully realised as a London gateway. For all those pax living in North/East London there is no option other than a potential 3hr drive round the M25 to access LHR and secondly LGW for the traditional "bucket and spade" destinations.
Nothing services these areas with a premium class long haul service.
Capetonian, unless your "extremely wealthy friends" are visiting the Costa del Sol or flying as freight then they would have no reason to utilise STN. Perhaps they should lease a GV and fly out of LTN next time....just saying!
And if Dubai is considered ghastly, I shudder to think what JFK/LHR/LAX etc would be deemed as!