1) Winds, as pointed out by planeguy. That's most of your time difference.
2) Great circle routes. The most direct route goes over the middle of the UK and Ireland and never over France. They do not appear straight on your normal map, but they are the straightest route when flying. Check it out in Google Earth.
3) The GC
distance is around 4550 nm. If you instead go all the way to the southern tip of Sweden and then on to Washington, it's 4620 nm or so (as measured in GE
). That's 70 miles added distance, or mere minutes at airliner cruise speeds. Diversions typically add less distance than you'd think.
I thought I was doing good trying to avoid those airport hotels... and look at me now.