Thanks all for your comments! We were delighted to come across these little treasures. Our first encounter with these lovely little people was earlier in the day in one of the streets leading to the Cathedral. We were all squeezed into a single file to negotiate the crowds and we were able to take a few photos of their passing us by (permission sought from their teachers 1st of course!). We thought how amazing is this to come across! Then to see them all assembled in the Plaza... There was a huge amount of interest from all the people there and loads of discussions ensued, and photography too. We were privileged to have this encounter.