I’ve come to enjoy train travel in Britain. Looking out the window, there’s always a variety of sights that remind me of Grade 9 history class: rolling meadows, low stone walls, and factories from the industrial revolution. On the train down to King’s Cross, there’s more than one instance signalling a more modern era.
King’s Cross is the central station for trains from the north (and east, as from Yorkshire).
Actually, the Heathrow Express and London Underground end up in the same concourse, and I’ve taken both. The difference is the number of stops along the way.