The number quoted by Ian for Fazakerley production of 169,807 is only up to rifle s/n S8823 & for BSA up to s/n BJ1337 there were tens of thousends of No5s not included in these totals given, in fact virtually all of 1946 & all of 1947 production No5s are not included in those totals, a fact i have tried to point out a few times for it to be completely ignored.
To Fazakerley production you can add 9,999 rifles for the prefixes T,U,V,W,X,Y,Z,AA,AB & AC or about 100,000 rifles.
Faz were allocated s/n blocks that were not used but as they were allocated AD,AE & AF as well (i understand there maybe a AD prefixed No5 out there) AE & AF were the non used s/n blocks.
Btw before anyone starts claiming they all have 4 digit s/n's & thats why the number is so low vs s/n prefixes, there are 1, 2 & 3 digit numbered No5's that have been observed.