Just wanted to drop an FYI to anyone going to London: Don't count on specific tube lines being open on weekends! This past weekend we returned to London from Edinburgh, got into the tube station to go from King's Cross to Paddington- the Circle Line would be perfect! Except it was closed for track repairs. So was the District line; we were fortunate to catch an alternate line for two stops, then switched to the Bakerloo to Paddington, so we made it, but was the tube CROWDED- sardine time. The entire weekend the two lines were closed- to compound the fun, we wanted to go to Trafalgar square, and knowing the easiest tube lines were closed, we decided to use the bus... except the bus service on the line we wanted was "suppressed" for that day. Ugh.
Just be aware of alternate manners of getting around on the weekends in London-
P.S. We got to Trafalgar by again using two different tube lines, so it wasn't impossible, just inconvenient!
P.S.S. We had a great time on our 3 weeks in England, Wales and Scotland!