Thanks for the site Colin. Very informative.
My Aziz has three vertical white lights on the mast (all wired up and pointing for'ad) so this would be OK, according to the 'rules'.
There are two at the back of the mast, shining down on the deck (for loading at night !!). Would any be required at the stern, do you think? If so, would they be on a small mast, or clipped on to the back somewhere?
Cheers...Ken