@wingpig - oh, are many back already? Term doesn't start for ~2 weeks.
For me it was several cyclists on the canal. It was really busy today - but some people still whizz through. I really don't mind pootling/stopping when I have to: If I'm in a hurry, and think the canal will be busy, I switch to the road.
It really annoyed me, as there were little children milling about. Any ideas how we can encourage other (non-CCE) cyclists to behave better? :D