Join Date: May 2006
Location: New York, London, Sydney
Programs: United GS/2MM, DL*P, VS*G, AA*EXP, Avis CHM, Hertz Platinum, Sixt*D, HH*D, HGP*P, Starwood*P
Posts: 9,880
VS is Virgin Atlantic. It's odd that you'd have one of those stickers departing Heathrow. Which carrier were you on?
BA, VS, and United certainly don't do it. Was this very recent on one of the newly moved-in American carriers (Continental, Delta, US Airways, Northwest)
It's a risk. It's quite likely UK Immigration knows when you left, but certainly not guaranteed. They can always ask next time, but you should know that even when they do check, they just look at the dates, they don't actually provide you with an exit stamp.