The walk in question began with a gentle stroll on some heathland in Exmoor, then a quarter of an hour scrambling descent (apparently 250m change in altitude) down to the sea. It then took over two hours to climb back up the hill, with ever-more-frequent stops for panting.
chrestomancy took one for the team and went ahead, rescuing us at the summit in his car. I'm not sure I thanked him enough :-D