UK George V farthings KM#808, KM#825

http://www.britishfarthings.com/Royal/3/All_George_V.html
This link gives quite a lot of detail on the different types of George V farthings, using reference to type numbers from Spink. The main Spink numbers are 4059, 4060 and 4061 which seem to tally with KM#808.1, KM#808.2 and KM#825 respectively. However, they do identify different sub-types, namely 4059A, 4059B, 4060A and 4060B, which deal with differences in detail on the obverse and reverse and with a change in the Bronze composition in 1923.

The reason I'm bringing this up is I believe that the Numista catalogue does not differentiate enough between the different types - at the very least I think KM#808 should be split up into two types - KM#808.1 and KM808.2. The difficulty is there seems to be some contradiction between Krause & Mishler and Spink and the link above. KM and Spink both say that there are two versions of the 1918, one dark finish and one bright. The link above, however, says there is only one version for 1918, namely 4060A. It also says that the change in the Bronze composition, from 0.950 copper 0.040 tin 0.010 zinc to 0.955 copper 0.030 tin 0.015 zinc, which presumably accounts for the change in finish, occurred in 1923, whereas KM and Spink say the change in finish was in 1918.

I know this is all a bit in depth and complicated, but if there are any UK mintage whizz-kids out there, I'd be glad to hear from them!

I've just done a bit more reading and it's not quite as I thought. The difference between the dark finish and the bright finish is nothing to do with the Bronze composition. Apparently, the decision to artificially darken farthings was taken in 1897, due to the fact that on occasion uncirculated farthings had been passed off as half sovereigns. The method adopted was to use acid fumes to artificially darken the coins giving them a "black" appearance, however on some coins this has resulted in shades down to light brown. This method of artificially darkening farthings was undertaken on farthings dated between 1897 and 1917. In my opinion, this additonal information seems to strengthen the argument to separate KM#808 in the Numista catalogue. Does anyone agree? Could someone from the team please assist?

Kind regards, Rick