This plate simply bears the legend of LMS BUILT DERBY and no year, why? I believe that given the decision to backdate so many locomotives of Midland origin that the decision was taken to simply re-brand rather than altering the year on the pattern. This isn't a problem of course for new build or for classes which had been built in large batches (so long runs of the same year plates) such as 4Fs but imagine trying to replate the multitude of engines Built and especially Rebuilt or even Boiler New (another way of saying Rebuilt) within say the the MR 2F class, a thankless task! Much easier to cast a pile of LMS Built plates. This would also mask the age of the locomotives that the MR had rebuilt so many times. The LMS did not need the data on the plate as build & rebuilding data was stored on engine record cards anyway. I believe this to be a totally new pattern on the LMS made at the same time as the built plate with year, one thing is certainly true there is a lot of size variation of this pattern pointing to patterns from patterns, probably to keep up with the sheer numbers needing to be made.
Size in inches- Any where between 10 & 1/4 by 5 & 7/8ths AND 10 &1/2 by 6, typically 10 & 3/8ths by 5 & 7/8ths. (hole centres 8 & 3/4 typical)
Pattern Rarity- Very Common