British Railways shades were all from the BS381 series.

STONE/BUFF/CREAM PAINT. The references to these colours can cause confusion, as they were prone to variation, darkened with age & weathering, and are often not precisely defined.  Clearly, real stone can vary from the red of Devon & Ayrshire to the grey of the Peak District, but to a painter, 'stone' is a pale buff colour, and that is the shade being referred to here by the use of the word 'stone'.  All these paints were made by mixing pigment with a white lead base. For the purposes of this web site, 'Stone' is a very pale buff with little yellow in the shade; 'Cream' is a similar shade containing more yellow, and 'Buff' is a darker shade which can approach a brown at times. If the railway company itself used the term 'Stone', however, I will also use it; the GWR & the SR used the term for colours that do not meet the above definition.