There were never any British Two and a Half-Sovereign coins minted.
A British Half-Sovereign has a face value of 50 Pence. They are made from 22 carat gold and, since 1980 have been issued as a collector or investment coin issued as either or Proof or bullion coin, or both, their actual value, depending on the year, is more likely to be anything from £140 to £200 GBP. See the link below for a currency conversion.
There was no 1811 British Sovereign or One Pound coin minted.
There was no British 1901 Two Pound or Double Sovereign coin produced.
There was no 1891 British Two Pound coin issued.
No. The British gold Guinea coin was a coin with a value of 21 Shillings and was 24mm in diameter. The Guinea was last issued in 1813 and was effectively replaced by the Sovereign. The British 22 carat gold Sovereign coin is a coin with a face value of One Pound (or 20 Shillings) and is 22.05mm in diameter. The modern Sovereign was first issued in 1817.
Half sovereign - British coin - was created in 1544.
A "British Sovereign" is the reigning King or Queen of the United Kingdom or, it is a 22 carat gold coin with a face value of One Pound.
The was never a British 10 Shilling coin minted. A Half-Sovereign was the equivalent of 10 Shillings.
Such a coin does not exist. The 1898 British Half-Sovereign was only ever minted at the Royal Mint London.
Such a coin does not exist. The first Quarter-Sovereign coin ever produced by the Royal Mint was minted in 2009.
Therre were no 1821 British Double Sovereign or Two Pound coins minted.
The Royal Mint has never produced a Quarter-Sovereign coin until 2009. There has never been a need for a Quarter-Sovereign coin, since the Crown (Five Shillings) did the job and, after decimalisation, the 25 Pence coin to a lesser extent.