Hi DDW,
I sailed a 43 last summer that stayed pretty dry up forward... Big heavy lid that could be dogged down pretty tight. I think the key is to have a oversized 'lip' that collects any ingress, and drains thru tubes on either side overboard... That, and probably replacing the neoprene gasket frequently...
hard to believe that Hylas doesn't have a thru-hull drain overboard, it must have gotten plugged with something at the bottom of the locker...
best regards,
Jon