Thanks Richard for your comments. The tugboat lights could be different in the waters of the Atlantic and UK. My resource is for the waters off British Colombia, Canada. The tow lights for the Great Lakes also have rules. So, if Neyrs is saying something different or others from the UK go with them. If you Google the question for the waters in your area, that can be a good source of information too.
Hope this helps,
Ron
Port Perry, Ontario Canada 🇨🇦