School trip to London

I walked along the south side of the Thames today. Just before the National Theatre complex on the South Bank I saw this blue crocodile walking in front of me. It turned out to be 20 to 30 school kids, all in blue coats and with blue hats. I was walking in the same direction for some time as I was aiming for Charing Cross and these kids were really well behaved, staying in pairs, keeping up with the couple in front of them and not spreading out under everyones feet. I was impressed.
My only problem was to get a good picture. I tried to picture the whole crocodile but only got the tail in the end

I don't know who they were or where they came from. If any one does know them please pass on my complements to a very well behaved class