In message , David
FitzGerald writes
I have an unholy set of flights booked from the US which culminates in a
transfer from Gatwick Airport to Heathrow Airport for the final leg of my
journey. I only have 3 hours between landing and take off of the next flight
(need 40 minutes check in) and I assume it will take me 40 minutes to get
out of Gatwick. This leaves me with about an hour and a half to get from LGW
to LHR.

A few more potential problems:

If you are arriving at the North Terminal then the mainline train runs
from the South terminal. That can easily add 15 minutes to the journey
(especially if only one shuttle is running and you've just missed one).

Be careful about the granularity of the mainline trains. It's no good if
the end to end time is an hour and a half, if the next train is in 20
minutes.

You might also want to check your airline's online arrivals page for a
few days, to see whether their flights are typically on time or late.

All in all I'd reckon you can only make this transfer by taxi, and even
then there's a more than 50:50 chance that you'll miss the Heathrow
flight. Perhaps you can find a taxi firm and call them from the USA
departure lounge to arrange the pickup. That way, if the plane looks
like being significantly delayed you aren't wasting your money.
--
Roland Perry