For eBay buyers who may be interested in purchasing old, circulated coins from Great Britain (United Kingdom), at least in part for their metal content - as silver bullion - here is a quick guide.

Overview

From the perspective of a silver coin buyer on eBay, there have been four distinct eras of British coins since 1800:

• Prior to 1920, British silver coins contained high purity, 92.5% (Sterling) silver.
• From 1920 to 1946, British silver coins contained 50% silver.
• From 1947 to 1971, some denominations of British pre-decimal coins issued for circulation were "silver-colored," however these coins were made of copper-nickel, and contained no silver.
  
• From 1971-on, some denominations of British decimal coins issued for circulation were "silver-colored," however these coins were made of copper-nickel, and contained no silver.  In addition, there have been some silver decimal coins minted in limited quantities as commemorative or bullion issues, typically in Proof condition; these coins were not intended for circulation.
  

The standard circulating denominations of pre-decimal British coins from 1800 to 1946 which contained 92.5% or 50% silver, included threepences, sixpences, shillings, florins, two shillings, halfcrowns, double florins, and crowns.

Update:  A table at treasurerealm.com concisely identifies the silver content in British coins from 1066 to 1947.  You can find this table by using your favorite search engine to search for "Silver Content of English Coins in Troy Ounces."  Thanks to eBay member external0 for this terrific tip!

Prior to 1920

Prior to 1920, British silver coins contained high purity, 92.5% (Sterling) silver.  These coins contain the following amounts of actual silver weight:

• Threepence (.0420 Troy ounces of actual silver weight)
• Sixpence (.0841 Troy ounces)
  (Krause and Mishler's Standard Catalog of World Coins, 19th Century Edition 1801-1900, First Edition, states that the silver content of the sixpence coin was .0895 Troy ounces from 1838-1919, as the weight of this coin slightly increased in 1838, but so far that hasn't been corroborated by other sources.)
• Shilling (.1682 Troy ounces)
• Florin (.3364 Troy ounces)
• Half Crown (.4206 Troy ounces)
• Double Florins (1887-1890) (.6727 Troy ounces)
  
• Crown (.8409 Troy ounces)

All the silver weights above are for as-minted, uncirculated coins. Circulated coins will weigh somewhat less overall and thus have modestly less silver content than listed above.

In some eBay auctions, sellers describe their lots of British silver coins in terms of their combined face value, in Pounds Sterling.  One Pound (£1) of pre-1920 British silver coins contains slightly more than 3.3 Troy ounces of actual silver weight, for as-minted, uncirculated coins.

One Pound is equivalent to 240 pence, if you should need to calculate the actual silver weight of silver coins comprising fractions of a Pound.  For instance, £1 20p of pre-1920 British silver coins would contain approximately 3.6 Troy ounces of silver (3.3 Troy ounces plus 20 pence/240 pence times 3.3 Troy ounces), and £2.25 of pre-1920 British silver coins would contain around 7.4 Troy ounces of silver.

From 1920 to 1946

From 1920 to 1946, British silver coins contained 50% silver.  These coins contain the following amounts of actual silver weight:

• Threepence (.0227 Troy ounces of actual silver weight)
• Sixpence (.0455 Troy ounces)
• Shilling (.0909 Troy ounces)
• Florin (1920-1936) and Two Shillings (1937-1946) (.1818 Troy ounces)
• Half Crown (.2273 Troy ounces)

All the silver weights above are for as-minted, uncirculated coins.  Circulated coins will weigh less overall and will have slightly less silver content than listed above.

In some eBay auctions, sellers describe their lots of British silver coins in terms of their face value in Pounds Sterling.  One Pound (£1) of 1920 to 1946 British silver coins contains slightly more than 1.8 Troy ounces of actual silver weight, for as-minted, uncirculated coins.

One Pound is equivalent to 240 pence, if you should need to calculate the actual silver weight of silver coins comprising fractions of a Pound.  For instance, £1 20p of 1920-1946 British silver coins would contain slightly more than 1.95 Troy ounces of silver (1.8 Troy ounces plus 20 pence/240 pence times 1.8 Troy ounces), and £2.25 of 1920-1946 British silver coins would contain around 4.05 Troy ounces of silver.

Threepence coins were also issued in nickel-brass, as well as silver:  During the last years of the circulating silver threepence coins, from 1937-1945, Great Britain also simultaneously minted nickel-brass threepence coins.  The latter are "brass-colored" and twelve-sided, and thus are clearly distinguishable from their silver counterparts.

From 1947 to 1971

From 1947 until the introduction of decimal coinage in 1971, British pre-decimal coins issued for circulation were made of copper-nickel or other metals, and contained no silver.  Since many denominations of these coins are "silver-colored," a few eBay sellers might mistakenly identify these coins as silver in their listings.

Some eBay sellers thus refer to their true British silver coin lots by using terms such as "pre-1947", "pre-47", "1946 and earlier" or similar language in their auction titles and listings.

From 1971-on

From 1971-on, British decimal coins issued for day-to-day circulation were made of copper-nickel or other metals, and contained no silver.  Since many denominations of these coins are "silver-colored," a few eBay sellers might mistakenly identify these coins as silver in their listings.

A small number of British decimal coins since 1971 have contained silver, but these have generally been commemorative or bullion coins minted in limited quantities and not intended for circulation.  One notable example is the "Britannia" series of 2 Pound silver bullion coins, which was first minted in 1997.

Unusual denominations: silver pennies, one and one-half, two, and four pence coins

Finally, in addition to the standard denominations listed above, ranging from the three pence coin to the crown, Great Britain also minted very limited quantities of silver pennies, two pence and four pence ("groat") coins.  These were dated from the early 1800s through at least the mid-1990s. Some were issued for circulation and others were minted in proof-like condition, for inclusion in Maundy sets.  In addition, Great Britain minted one and one-half (1-1/2) pence silver coins from 1834 to 1870.  The coins in these small and unusual denominations have significant numismatic value above their relatively nominal silver content, and are typically not purchased as bullion coins, except perhaps as badly damaged or worn "culls."