Thank you for the references which give an origin for the story - even if they cast doubt over whether it was the bridle or the stirrups that the was hanging onto. (Surely the bridle would upset the horse more than the stirrup?)

I don't think it hard to imagine someone who was drunk, injured, or going through mud hanging onto the stirrup of one horse and being helped along; but the more I think about it, the less I like the idea of hanging onto two horses (both presumably rather excited and in a hurry) while they trot along, cross-country. Am I just being a party-pooper?

Rory