The Black Watch and Boudicca are genuine sister ships are are fairly alike in lay-out except for their public rooms. The original ship, Black Prince, is small and elderly but has a loyal following. Braemar, newly "stretched", is very much a sub-trpopical ship and spends the European Winter in the Caribbean. The ships are Norwegian-owned but very British in style.
Cruise ships, 5. Black Prince, Black Watch, Braemar, Boudicca and their newest and largest the Balmoral (has been previously known as the Crown Odyssey and Norweigian Crown) .
Why dont you pop into a travel agents and get a Fred Olsen brochure. It will show you all the fleet, sizes and itinererys.