There appears to be two different examples of the 1826 'Farthing' coin of George IV for sale on eBay. (Both described as 'Farthing', AE22mm., 4.75gm.) I can see the differences, but can anyone please tell me why they exist? (My education needs adding to.) Coin #1 - a/ Georgius IIII, (as opposed to Georgivs IV on coin #2) b/ Draped bust, (as opposed to bare bust on coin #2) c/ Oak leaves behind Brittania, (as opposed to no Oak leaves) d/ Brittania reaching behind for shield, (as opposed to beside) e/ Date under Brittania, (as opposed to date under George IV
The first is KM#677, which is an earlier type struck in 1821-1826. The second is KM#697, which was struck 1826-1831. So it seems to me that 1826 must have been the transitional year, with the first type struck in the earlier portion of the year and the second type struck later in 1826. To use an imperfect analogy, this would be akin to the situation with US cents in 1909, when we had Indian Head cents for the first portion of the year and Lincoln cents in the latter portion.
@lordmarcovan While I thank you for them, I am unfamiliar with your references KM#677, and KM#697 Thank-you, kind sir. Your remarks spurred me in the direction of an old copy of 'Spink' (1998) wherein I found reference (as you correctly noted) to a 'First Issue 1821-1826, (3822)' and a 'Second Issue 1825-1830, (3825)', which accounts for the 'overlap'. Thank-you, again.
These are catalog numbers from the Standard Catalog of World Coins, which uses KM, Y and C #'s. You will see people referring to these very often on the forums, as it is the primary general reference for world coins.
Yes, change of design half way through the year. This happens occasionally in British coins - for example the same bust change happens in 1825 on the Shilling coin. It is even more radical in 1727 where you can get coins with either George I or George II's head! All adds to the size of the collection. Krause is the best general reference for all World Coins, but if you are specialising in a Country, then you need the local guide, and for British coins Spink is the best. It comes out every year, but not a lot changes so I usually only update every 5 years or so.
The "KM" numbers stand for Krause-Mishler, who were the publishers of the Standard Catalog of World Coins, as @Numismat mentioned.
In 1825, after a 24 year delay, Great Britain and Ireland enacted a monetary union. Some time in the middle of 1826, the British coinage designs changed to reflect this and the result is two types of farthing dated 1826 - no one knows which type is scarcer. In the higher grades, lots of little errors and varieties can be seen. See more here: https://oldcurrencyexchange.com/2018/01/05/obrien-coin-guide-gb-ireland-copper-farthings-george-iv/