The Birmingham proof was 1962 George; the crossed halberds with NB on the L barrel flat.
Odd looking '12' and .729" doesn't fit 13/1 which would have been .719 - .728"?

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Under the 1954 Rules of Proof the “Highest Mean (transducer) Service Pressure” for 2 1/2"/ 3 tons was 8,960 psi = 618 BAR

I'm interested in the Ferlach marks also

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