The post card of what we always called the clapper bridge brought back happy memories of picnics at Wycoller in the 1950s.
It also brought to mind the expression 'to go like the clappers' (to go very fast) and I wondered if there might be a connection. However, a quick browse on the internet indicated no such link - suggesting rather that these clappers referred either to the clappers of bells (and more specifically to the clappers of the bells of hell); to fast-running rabbits (escaping from their hutches, called clapiers in French); or, even, to testicles and sexual activity! (For more detail, on possible derivations, see Michael Quinion's World Wide Words on:
http://www.worldwidewords.org/qa/qa-lik3.htm Ruth