but there have been other emergencies into LHR where ATC have directed the aircraft to other, secondary LON airports?
Some examples would be of interest
As well as clarifiying by what you mean by "direct"? I tend to tell ATC where I will be diverting to, after making a team based decision with my colleague, not by asking ATC. Else sims would be a lot easier
If they read their pre-prepared speech about "LHR being busy go elshewere blah blah" I turn the RT down for a couple of minutes