Change over from Mk1 to Mk1* was 'around' the 12C to 15C prefix numbers. 120,000th to 150,000th rifle between those numbers examples of both have been found, and even a very very few occasional Mk1's after 15C. One can only speculate that they were 'lost' at the bottom of the stillage and were eventually picked up and used.
I asked about the cross-bolt thinking it may have been scrubbed in India, the OP answers there isn't one, but I think you may be thinking of THE 'bolt' of which there are pictures