In 1478 a third mark, reporting a letter of the alphabet to be change each year at the beginning of the month of May, was introduced. The use was not in the intention to allow the posterity to identify the year where the silver was hallmarked, but those to make identifiable the Assay Master in charge at that time, in order to comminate him a penalty in case of marks struck on under standard silverware.

In London only 20 letter were used (all except J, W, X, Y e Z); in Birmingham all the alphabet; in Edinburgh all the letter except J. In Sheffield, in the period between the opening of the Assay Office (1773) and 1824 the date letter randomly changed. In Glasgow the use of the date letter was suspended for most the XVIII century

The font of the letter was changed each cycle, combining the use of capital and lower letters and different shape of punches, in order to cover with different combination all the period of time th Assay master was in charge.

Since 1975 the date letter was unified for all the survived Assay Office in the UK (London, Birmingham, Sheffield and Edinburgh), and changed at the beginning of January each year. Since 1999 the use of the date letter became an optional.

In 1720, when 'sterling' standard (925 ppt) was reinstated after the compulsory use of Britannia standard (958,4 ppt), a 6 pence duty per troy ounce of silver was imposed on silverware production and trade in UK. An item of about 33 oz (1000 g) as subject to a duty equalling a 2005 value of about 120/140 dollars, that is to say the same price requested by a silversmith for its manufacture. The temptation for a silversmith to "dodge the duty" and keep this money for himself was consequently very high, in spite of a death sentence imposed for hallmarks forgery or transposing. Some dishonest silversmiths used spoons or little salt cellars (paying a small duty for the standard verification of the Assay Office) cutting their hallmarks and soldering on pieces of higher weight.

The duty on silver and gold was repealed in 1757 when a tax for any activity producing and selling silver and gold was introduced.

Since December 1784 a new duty (to support the expensive for the secession war in the North America but abolished only in 1890), was imposed and a new mark, the profile of the reigning Sovereign was introduced to demonstrate its payment. So, on silver marked between 1784 and 1890 we can find the profile of George III (1784-1820), George IV (1821-1830), William IV(1831-1836) and Victoria (1837-1890).

All these marks show the Sovereign profile looking right with the exception of the mark of George III in use between the first of December 1784 and the 30^th of April 1785 (the so called "incuse", being impressed in depth on the silver), and those of Queen Victoria. which are looking left.

Between December 1784 and July 1785 a special marks for retrieval of the duty paid on exported items (the erected silhouette of the Britannia) has been in use.

In Ireland the duty was introduced in 1730 and a duty mark (the Hibernia) was struck on silver to demonstrate its payments. Since 1807 (after the Union Act of Ireland with England and Scotland) and the adoption of the English system for hallmarking, the Hibernia became the symbol of the Dublin Assay Office and the current duty marks in use in England was adopted.

During the XX and XXI some optional commemorative marks (mainly royal jubilee marks) have been introduced. Jubilee marks are very similar to duty marks (not to be confused with) as a sovereign profile is represented. Their have been use in:

• 1936/7 (25th anniversary of George V coronation);
• 1953/4 (coronation of Queen Elizabeth II);
• 1977 (25th anniversary of Queen Elizabeth II coronation and 750th anniversary of the royal chart for the Goldsmiths' Company;;
• 2002 (anniversary of Queen Elizabeth II coronation);
• 1999/2000 millennium mark (a cross with the number 2000)

Since 1975 some change occurred, in particular:

• new standards for silver have been introduced (800 and 999 ppt);
• the silver standard is now struck as Arabic number in a oval;
• the symbol of the Sheffield Assay Office (a crown) was change adopting the Tudor rose to avoid confusion with the mark used for gold;
• the date letter was unified for all the survived Assay Office in the UK (London, Birmingham, Sheffield and Edinburgh), and changed at the beginning of January each year;
• the sterling mark (thistle) for the Edinburgh Assay Office was change in the lion rampant;

Since 1999 some more changes have been introduced:

• the sterling mark (lion passant) was adopted by all the Assay Offices (including Edinburgh, instead of the lion rampant);
• the symbol of the London Assay Office (the leopard head) was also adopted for the Britannia standard (instead of the lion head erased);
• only the maker mark (now known as sponsor mark) the finesse or standard (Arabic number in a oval) and Assay Offices marks remain compulsory; other traditional marks (Britannia and lion passant became voluntary marks;

Gold (at first 19.5, then 22 and 24 carats) was marked in the same way as for silver until 1798, with the only difference in the use of the lion passant also in the period when was in force the Bbritannia standard (1696-1720). As a consequence of the introduction of a new fitness for gold (18 carats), a new mark to be impressed on item conforming to this new standard was introduced (a number equals the carats and a crown). The crown was usually impressed above the number, bat one can find some item were this two marks were separately struck.

22 carats gold was marked as for the 18 carats finesses only since 1844, but always with the number and the crown impressed in sequence.

Between 1816 and 1844 a rare mark (the sun) for 22 carats gold has been in use at least in London.

In 1854 new gold standard of 9, 12 and 15 carats have been introduced for commercial reason related to the export of gold item to the North America.

Since 1933 gold standards are only four (9, 14, 18 and 22 carats). The new marks report the number of carats and the finesses per unit of gold (e.g.14 followed by .585 for 14 carat gold standard).

1  19 1/5 carats (1300-1476) and 18 carats (1477-1544)                                                                                                                     

2  18 carats (1544-1574) and 22 carats (1575-1843)                                                                                                                          
3  18 carats (1798-1974)                                                                                                                                                                  

4  22 carats (1844-1974)                                                                                                                                                                  

5  15 carats (1854-1931)                                                                                                                                                                  

Since 1842 any silver item imported in the UK must be checked for the conformity to sterling or Britannia standard, with the formal exception for items manufactured before 1800. In 1883 a mark (a capital letter F) was imposed to indicate the foreign origin of the item (with some exception for small items for which hallmarking can result difficult). This mark generated some problem, because it was very similar to a date letter.

In 1904 hallmarking on import silverwares was completely revised and integrated in 1906 to avoid confusion between the introduced marks (e.g. for London) and similar trade marks.

In 1976 a common agreement on imported/exported precious metalwork was subscribed by Austria, Finland, Norway, Sweden, Switzerland, Portugal and UK, later integrated in 1983. As a consequence of this agreement a common mark for finesses (convention mark) was adopted.

Convention marks in force since 1976 in Austria, Finland, Norway, Sweden, Switzerland, Portugal and UK and since 1999 also in the Check Republic, Denmark, Ireland and Netherlands.

Although not compulsory, each Country can maintain own town and traditional marks (e.g. the lion passant, the lion rampant, the date letter, the 1906 import mark, etc.). Special marks (not reported in the table but available at the link below) are struck on exported silverware produced in the UK with finesses standards of 800 or 830 ppt, not in use in the UK internal market.

On silver marked with the convention marks no more control should be dome to within the Countries that signed the agreement.