No real chance of bottoming that one out I'm afraid, as the lists from Leeds Armoury only give the final Enforcer/Envoy number ie 099 etc no original serial numbers appear to be recorded on anything I have access to.

I suppose there was no need for cross referencing at the time of conversion, they needed a number and it made sense to numerically start afresh.

Suffice it to say, if yours was an Enforcer it would be fairly clearly marked in some way. I don't hold the Envoy lists.