Tru-Color Boxcar Brown (TCP-011) - Model Railroader Magazine

Interesting answers being contributed.

As an aside  I remember reading about colours of London & North Eastern Railway rolling stock.  Although they should be the same, tins of paint in the Darlington  workshop were slightly darker than paint in the Doncaster workshop?

Also mentioned was the paint on rolling stock fading over time.  Once again they were the same colour, two wagons side by side would 'look different'.

Then there is the case of 'weathering'.  Rolling stock used on long journies rarely were cleaned.

One interesting point mentioned (imo)  it was fround upon having dirty locomotives.   Railway Companies employed 'an army of cleaners' to ensure smart looking rolling stock.

David