Thanks for the replies. The Airbus did drop suddenly. As it approached it seemed to flare as normal and then suddenly fell. I actually winced as I saw it drop because I knew it was going to be a hard landing. It then literally bounced back up in the air and seemed to "float" for a few seconds and then then power was applied. It remained at a similar level for a few seconds then slowly began to climb then the gear went up after that. On final approach it had already seemed somewhat wayward dropping surprisingly sharply a couple of times before picking up again. It was distincly unusual compared to the other landings I saw during the hour or so that I was watching. For the record it was a Thomas Cook flight. The reaction of people around me at the time was identical to mine with lots of expletives.