NOTES ON RARITY-
Where I describe a particular pattern as common or rare or whatever... this is a reference to the commonality of the pattern not to what locomotive the plate came off. Typically the Crewe 1936 illustrated is a very common pattern but not to common from Jubilee's or Duchess types. This is not a guide to rarity based on loco type.
Are all in inches and where possible all known size ranges will be given, there seems to be alot of confusion re sizes of plates! Plate sizes vary slightly due to grinding but NOT in the main from casting unless there are multiple patterns made from master patterns, or patterns from Patterns.... Derby is particularly bad for this giving similar types of plates with up to a 1/4 inch difference in some cases.
Plate sizes given here are fairly precise but a difference of a 16th between examples is not uncommon. Differences of say 1/8th of an inch upwards are in my opinion indicative of copying or of a different pattern as stated above. Replicas are a constant problem as with the LMS Rebuilt 1920 Derby being a regular on the net!
Shrinkages in Iron are 1/100th, 1/96th in Aluminium and 1/76th in Gun metal/Brass thus copied plates as a norm tend to be 1/8th down on proper sizes where know.
The opinions offered herein are purely my own and as such are based on my measurements and research over the last 17 years.
Brass (Common type alloy Copper & Zinc)
Bronze (Leaded Gun Metal as used in Steam Fittings etc, alloy copper, tin, zinc & lead)