There are so many rare British Coins dating back over a thousand years, that I could not possibly list them here.
This sort of information fills books with hundreds of pages detail.
Your local library may have a coin catalogue listing all British coins dating back to Roman times.
There are that many British coins minted over the past 1,000 years that could be considered to be rare or scarce, that they could not possibly be listed here.
British coins have been minted for well over 1,000 years. There are hundreds if not thousands of rare British coins from this period. Other than the odd "error" coin that might turn up from time to time, there are no general circulation decimal coins that could be considered to be especially rare.
If you refer to British general circulation Threepences, there are no rare coins.
This is an incredibly broad question with no real answer. Since British coins have been issued for well over a thousand years, there are numerous rare and expensive coins and really no data to show what is the most expensive of the old British coins.
As a general rule, and other than for the odd error coin, there are no rare British decimal coins. There were many non-circulating coins minted as "Proof FDC" which would have bought by collectors when they were released, but they are not especially rare either.
None of the British London 2012 50 pence coins could be considered rare. The least number of any type that was minted was 1,125,000. There were 1,161,500 Judo 50 pence coins minted.
No, they are not rare. British coins were minted that way for hundreds of years. The process is called "Coin Rotation" or "Die Axis". British coins were minted with a 180 degree rotation, so that reverse is 180 degrees out of alignment with the obverse. The practice was gradually discontinued during the course of the 19th century. By 1887, all coins were minted without "coin rotation". Many other countries used "coin rotation" on their coins and not always at 180 degees.
Assuming you refer to 20th century British general circulation Halfcrown coins, none are currently rated as rare. The 1927, 1937 and 1950 "Matt Proof FDC" coins are considered to be of the highest rarity. The 1952 coin is unique, there was only one made.
1933 one penny, 1952 half crown, 1936 Edward VIII brass three pence...
Most British One Shilling coins from the past 100 years would not be considered rare. For more detail, you would need to provide the date on the coin.
I bought most of my rare coins at auctions.
We cannot see you rare coins. Since we cannot even see your rare coins, we do not even know if your coins are indeed 'rare', what they are, their condition, when they were made - we do not know anything. Please specify in a different question what your coin is, the date it was made, and the condition it is in.
Yes, there are rare coins from the Bahamas. One of the coins is a 1991 Bahamas gold coin where only 500 of them were made