folks in line to clear passport exit process. for the onward flight
Joe, are you just connecting at the London airport, and not heading into town for a stay? I’m not certain that lines will be shorter at Border Control, if other international flights just arrived, too, and the 15 minutes might not make much queuing difference.
When Icelandair first served Denver, Gatwick was the only option (still is), and it worked well. We stayed closer then to Victoria Station in London. When British Airways first included Denver flights, same thing, it was Gatwick. Now that the Denver BA flights use Heathrow, that’s our only option, and we now happen to stay closer to Paddington.