I watched the Royal Blue coming in to Mt Royal station heading to DC about every other week at least. It was usually pulled by an A-B set of the early E units and usually had 8 cars. At that time number 51 was the lead unit if I recall correctly and 51X was the trailing B unit. This was in the late '40's and early '50's. After that it had a mix of E6's through E8's. Always had 2 units whenever I saw it.
If I was fortunate there would be a northbound freight pulled by 2 to 4 of the electric motors going through as we waited for the Royal Blue. The B&O had 8 of the electric motors and 4 was the maximum permitted on a train.
There was a tower located in Mt Royal station on the west side of the tracks near the tunnel to Camden station. It was removed in the early '50's as I recall.
