The problem with the NRM is there doesn't seem to be any consistency with their standards. At one point they didn't want Oliver Cromwell painting, become the paint that was on was done by BR. They didn't want D200,when it was restored they did! The prototype mk2 was left to rot until the mid Norfolk took it, yet their core collection of coaching stock is mainly one off special vehicles that are not representative of the stock on the railways of the UK at any given time.
Basically if you were from another country and knew nothing about railways you'd think that in the past we all rode about in total oppulance pulled by highly polished brass and copper destined locomotives until 1968 when....... Well they don't really say what we did