Originally Posted by
LondonElite
It depends on part on what passport you hold, what class of travel you are in, and whether you have hold luggage. And, depending on the volume of the day, this can be anywhere from 30 minutes to over two hours.
Heathrow immigration has two sides, one for British and EU passports and the other for everyone else. The everyone-else line has a fast-track for biz class but you'd need to be sure to get a voucher from the air-crew, and often the fast-track is no faster than the regular line. In the early mornings when lots of US planes arrive it's a third-world-style shambles much like the foreign-immigration at JFK or IAH, you could be 1,2 or 3 hours in line.