Following the rationalization of the railways in 1922, I believe it was called an amalgamation, the London Midland and Scottish Railway selected Crimson Lake as its primary livery colour. What a wonderful colour this was. And still is! It exists on many of the maroon coaches seen on steam preservation lines. Crimson Lake came from the Midland Railway, that which steamed north out of St. Pancras to serve the backbone of England. The Midland Railway was a fastidious company that kept their trains spotless.
Another amalgamation saw the introduction of Malachite Green on the Southern Railway system. Malachite is one of my favorite minerals - I occasionally buy a piece when in Africa - and the once ubiquitous green carriages and steam locos on the southern always looked good in that colour.
In 1948 the four companies that were formed in 1922 were nationalized. Worn out after WWII and needing far more important investment than a pot of paint, they got a new livery for passenger coaches. I suppose Maroon and Cream would have been the correct terminology but I only ever knew the colour scheme as "blood and custard"!
One steam locomotive we see regularly is the SDJR 7F Class 2-8-0 number 88. This has been painted in the Somerset and Dorset Joint Railway's original Prussian Blue scheme and it looks great. But ironically I understand that this colour was never applied to No. 88 when it was built and operated by the SDJR!
God's Wonderful Railway (also Goes When Ready), the Great Western Railway of I K Brunel, had distinctive colour schemes that live on today on several steam preservation lines. Locomotives that were used for passenger trains were painted in Middle Chrome Green (close to Brunswick Green) while the carriages came in two-tone Chocolate and Cream. These gentle colours suited the GWR and its territory. Something that cannot be said for the garish colours employed by the modern First Great Western TOC.