So you got 156, 156 and 1567! Amazing. David Howroyd told me that they found a mistake/duplication in an export L2A3 gun order. That caused a bit of confusion but it was 'corrected by the clever alteration of one of the figures (say, a 1 into a 4 or so.....) when a similar number was due to be engraved. Difficult because the numbers were engraved VERY deep to avoid 'tampering'