I have no idea why I was worried, but whatever it was he certainly picked up on it from the moment I was in the saddle. Yep, he was skittish from the beginning, and I must've been really tense with my legs. The first canter was fine, but by the time I took him round on the other rein he was really taking the mick. Must sing to myself next time - I remember being made to sing "Nellie the Elephant" when I was learning to canter!
