In message <Z6KdneXFpKnmUMjanZ2dnUVZ8sKlnZ2d@eclipse.net.uk>, at 
21:58:16 on Tue, 4 Dec 2007, Dave <d@p.com> remarked:
>> The problem is you need to be able to operate a transit system that 
>>remains
>> 'airside' for it to work.  Not impossible but very difficult and very
>> expensive.  It would require dedicated infrastructure at each airport 
>>and  I
>> doubt the traffic handled would justify the cost.
>>
>
>Is that true? We've already seen there is a distinction between 
>"transit" and "transfer" passengers.

I can't immediately think of what that distinction might be in the UK.

>What happens today if I'm transferring at Heathrow and I need to change 
>from T4 to T1, for example?

Did that last month. You walk all the way to the west of T4, catch an 
airside bus via the cargo tunnel to the "Connections Centre", get 
x-rayed, but not checked by immigration, then take a travelator to T1 
departures lounge (emerging near the BA lounge).

>Or Gatwick North to South?  Surely I go landside, then re-check in

Only if transferring to a low-cost airline that mandates landside 
checkin.

>(even if my luggage doesn't)?

-- 
Roland Perry