Have to say, I’m interested as to WHY they have the markings ?
The Centaur IVCS with a 95mm gun were given to the Royal Marines as support tanks with Sherman OP tanks. It was envisaged that during the run in to the beach, while the landing craft, the Centaurs while still on board, would lay down supporting fire. This wasnot an easy task so to facilitate this, a complex compass arrangement was painted around the turret allowing the spotter to get the turret to point accurately towards targets as the tanks were not equipped with indirect fife sights.
Each of the five Batteries was subdivided into four Troops, with each Troop equipped with four Centaur IV and one Sherman tank as (command/OP), giving a total of 80 Centaur and 20 Sherman tanks in the entire Group. RMASG was disbanded two weeks after D-Day (D+14).
Now, it's NOT a new idea. In the 18th/19th century, there were large 'boat-mortars' which used a similar marking system (on the mounting board of the mortar)