Thanks, @Mayner, very informative as always.
So, from a manufacturers point of view, there'd be a lot less mileage from a P47 than there was from P42, or would be from a P20?
It's a shame that they have had such limited useage through their life as they do cover quite a long period.
An awful lot of the containers on the liners today, according to YouTube videos, appear to be 45ft, so some 47ft wagons are essential for 2020 modellers.
I'll have a read of Nile's thread on RMWeb, thank you!