The Date Letter

Date Letter Sequences Date Letter Decoder

Towards the end of the 15thC it was ordained that the "keeper of the touch" (the Assay Master) should be responsible for maintaining the standards of gold and silver presented for assay. This was a result of continuing complaints regarding substandard wares which did not comply with the Sterling standard. Towards this end, the date letter system was introduced, devised to ascertain the year a piece was presented for assay and to trace offending makers (and Assay Masters).    
The date letter sequence starting 1697 (London)  
The first full cycle of date letters in London began in 1478 with "A" and continued in an unbroken series of twenty year cycles (omitting the "J" and from "V" to "Z") until the Britannia standard was introduced as a result of the "Great Recoinage" of William III in 1696.
The date letter sequence starting 1975 (London,)  
A new twenty year cycle was begun at this time and this continued, differentiated by changing styles, cases of letter and shield shapes until the four remaining Assay Offices were harmonised with the Hallmarking Act, a new cycle starting with "A" on the 1st January 1975.    
Until 1660 the date letters were changed on St. Dunstan's Day (the patron saint of goldsmiths), May 19th. On the restoration of the Monarchy in 1660, the date was changed to Oak-apple Day (the King's birthday), May 29th.    

The Edinburgh date letter system was adopted in 1681 and at the same time the "Deacons Mark", which was used as a standard mark from 1457, was changed to the Assay Masters Mark alongside the date letter which was changed in October, following a twenty five year cycle. One happy result of this five hundred years of legislation as far as the modern collector is concerned, is that a piece can be dated with an accuracy that many collectors of other antiques and works of art would envy.