BA will not allow you to board at LHR without a Visa if you need a Visa.
I have a British Passport and do not need a Visa. I have done the turn around three times. Transit desk is always crowded and I have always gone thro immigration and customs which require less than 5 minutes. You can avoid the long walk up and down by hailing an electric cart. My last two trips it took me less than 30 minutes to return to the departure area. I am doing another turn around on 20 /21 July and will go the full circle
The terraces lounge is fine and better than the crowded Emirates lounge.It has 4 internet terminals, cappucino, good snacks and the usual liquor. Duty free is OK for alcohol and perfumes but electronics are more expensive than USA.

[This message has been edited by drbala (edited 07-09-2002).]