Queen Mary 3 Ton Trailers:
Often Towed by 3-Ton Commer 4x2 Trucks
From Hitch: 3 Large 'X' bays,  Wheel,  2 Large 'X' bays

Queen Mary 5 Ton Trailers:
Often Towed by the Iconic Bedford 4x2 Trucks
From Hitch: 3 Large 'X' bays,,  1 Small 'X' bay, Wheel, 1 Small 'X' bay, 1 Large 'X' bays

Construction much more obvious from the new pics.