So what do we think the time differences are bewteen the teams.
My best quess is that Rob and Amber arrive at the pitstop in Potter's Field Park is early afternoon. They arrived at 9:00AM (hey, disregard all those shots of clocks at Waterloo Station they read 8:30 and 8:45AM) One shot of Big Ben from the London Eye reads 11:30. They went first to Abbey Road after taking express in from Heathrow, so give or take one hour here. Quick ride on Jubilee Line to Waterloo Station and London Eye which takes 30 minutes to resolve. So at most another hour. Now its 11:00AM. Back and forth on the underground sleuthing the Brain detour. Another hour at most. At noon they head toward the Millenium Dome. At most 30 minutes (Ron and Kelly take cab and we hear him say it took an hour.) Rob takes 4 tries to complete driving task and he says he spent an hour doing it. Then eight miles to Potter's Field. So now it is now about 2:00PM.
Ron and Kelly arrive at Millenium Dome after Ron and Kelly leave and then have to wait another hour before they can start driving test, so now it is 3:00PM. Kelly takes 7 tries to complete test and it is getting dark so it is now around 3:50. By the time they finish and ride cab to Potter's Field it is now dark and the city lights are all on, and Tower Bridge is brightly floodlit. So my guess is that R/K arrive at about 4:30; this give Rob and Amber a 2.5 hour lead.
When R/K complete Roadblock, M/G and U/J are still at it. It takes Joyce 6 tries so say an hour and a half. It is now quite dark out and by the time they arrive at the pitstop it looks to be even darker. (You can barely see them run through the park and this is with a camera lens wideopen) So my guess here is that it may be around 6:00PM and R/A have a four hour lead.
But it makes no difference, they probably all end up on the same flight to Jamaica! Air Jamaica has a non-stop flight leaving at 12:40PM arriving in Montego Bay, Jamaica at 6:05PM. American Airlines has a flight to Miami leaving at 9:45AM but not arriving with connection from Miami until 8:35PM. Air Jamaica flight to Kingston connects through MBJ.
And we do see all three teams running together in Jamaica. So again bunch, bunch bunch and there goes your four hour lead!!