You might be right about the AR, it looks like it has the wide pillar on the front upper deck, however, the headlights seem too small, also the fleet No plate seems too high on the front, were these always placed in the same position?. I would have almost said it was a 'Queen Mary' but the single n/s fog light is missing, some may have been removed/not fitted I dont think the AR had these. The AR and Queen Marys had similar shaped n/s mudguards.
I need to study the photo a bit longer but dont have the time now.

Anthony.