Have been into Europe lots of times on the bike and never fitted them and I've never seen them fitted to any UK bikes on the ferry. In all honesty, I never thought you had to have them on a bike, but could very easily be wrong! I always fit them on the car though. What about, the obligatory warning triangle, fire extinguisher, first aid kit, fluorescent jacket and spare bulb kit you have to have in your car? I don't think you have to carry any of these, but a bulb kit is probably a good idea, costs little and doesn't take up a lot of room.
