Mark number "blocks"- origin of practice?

Hello all,

I’d like to find out when and if possible why (or rather, how) it was decided to use discrete blocks of Mark numbers in some cases. I suspect it began with engines, but early examples for aircraft are:

overseas manufacture:
Australian Tiger Moth
Canadian Hurricane and Mosquito
etc.

Spitfire- Griffon engined Mk.IV renumbered to Mk.XX

If it is true that it began with engines (Merlin X, XX, etc) then I’d ALSO like to know about its introduction with aircraft.

Over to you…

bob