Hamble HM seem to have sorted it all out now. I always run two turns of the genoa halyards round when furling. Going to check on our own boat at Mercury shortly, if any other berth holders there want me to look, just let me know your berth and I'll report back.
I was looking at the webcam at Watchet Harbour earlier and noticed a boat with flogging headsail that had come unfurled; had another look 30 minutes later and it had brought the mast down
Our Marina staff are really good and check the boats before a storm, after a particularly bad storm they had set up an extra line to limit the movement of my boom and I am told they also drop the water level before a bad storm (one of the advantages of a lock compared to queuing up to get in on a sunny bank holiday