'M' - Hand - 'GF'
Anyone with a copy of Sir Charles Jackson's "English Goldsmiths and their Marks" (the original un-revised version) will know that he tentatively suggested that these marks were representative of the city of Belfast.
Why did he come to this conclusion? Probably for two reasons, the most obvious of course is the open hand mark resembling the Red Hand of Ulster and the other being that the highest concentration of discovery of pieces with this mark appeared at the time to be in Northern Ireland.
We now know that these items are in fact Maltese and would date from the period 1800-1810.
Besides the open hand mark, Maltese silver of this period carries the makers mark and also a single letter that denotes one of the three silver standards permitted at this time, the standard was divided into 12ths and as follows:-
"F" (French Silver) 11 1/2 parts Silver to 1/2 part alloy
"R" (Roman Silver) 11 parts Silver to 1 part alloy
"M" (Maltese Silver) 10 1/2 parts Silver to 1 1/2 parts alloy
The 'Open Hand' mark is thought to have been in use during the period 1800-1810, after 1810 the mark was replaced by the 'F', 'R', and 'M' being surmounted by a 'Stag's Head'. The 'Stag's Head' mark was a short-lived device and disappeared sometime between the period 1813-1824, although the 'F', 'R', and 'M' marks were to continue until the Ordinance of 1856 changed the regulations.
So why were so many pieces found in Ireland? The answer is a simple one, when the British wrestled the French out of Malta in 1799/1800, it was the Royal Irish Fusiliers, whose headquarters at that time was at Armagh, that were used for that campaign and presumably they brought these items back with them when they returned home.
I suppose there is a possibility that the hand was added as a hallmark to denote the victory over the French, but if so an error occurred, the Red Hand of Ulster is always right handed where as the Maltese Silver mark is left handed.