Transfer between Heathrow and Gatwick airports

It's an hour drive, at best. No idea how long the transfer bus takes. Call the whole mess an hour and a half for grins.

Getting out of Heathrow can take up to an unpredictable hour.

You'd need to be at Gatwick an hour and a half prior.

The math doesn't work for me.

Your wording on the itinerary isn't quite clear. Normally, if there's a connection screw-up that's the carrier's fault, they'd move you along on the next available. I don't quite see how an airline could be responsible for ground transportation it doesn't provide - - eg, what if you drove and stopped for a big lunch? I just can't see how some guidelines would apply. But again, if they booked it as a continuum . . . .

The standard IATA minimum connection time between LHR and LGW is 2:30. This was set decades ago and most airlines work to at least 3 hours up to 4.30 today. On a single ticket the airlines would pick up the changes in the case of a delay, but since BA only run one flight a day, for only 5 days in a week you could find your travel severely disrupted.

Thanks, Ed and Marco! Sorry for the delay - I just saw your responses. (Wish the email notifications were still used.) I think I need to talk to American.

I faced pretty much the same issue on a previous trip, when I had to switch airports. National Express bus is the best/easiest/cheapest alternative, but it's still an hour's drive. Ed is right that you have to be at the other airport well ahead of the next flight, since you have to go through security and all again. In my case, I arrived at LHR at around 8:00, and had a choice of an 11:30 flight or a 3:00 flight out of the second airport. I chose the second option. As it happened, everything worked like clockwork, there was virtually no line at immigration, and I got to the second airport in plenty of time to have made the 11:30 flight, so I had to cool my heels for a couple of hours. But if I had relied on that, it no doubt would have gone completely sideways.