For every year they have been minted, they have been minted in huge quantities, so they are neither rare nor valuable.
The best you might get for an uncirculated Proof FDC coin might be £3 GBP.
No. The new design coins introduced in 2008, have the date on the "heads" side.
They are not valuable, they are still in circulation and are worth 50 Pence. Newer coins only have some value if they are in mint uncirculated condition or, if they are Proof coins. Due to the extra work put into them and the metals they are made from, Proof coins are more expensive to buy in the first place.
The British 2 New Pence coin was "invented" by the Royal Mint, with an obverse design by Arnold Machin and a reverse design by Christopher Ironside. 1,454,856,250 coins were minted in 1970 for release on "Decimal Day" on the 15th of February, 1971.
Check again. The British introduced decimal currency on the 15th of February, 1971. Since then, 25 Pence coins have only ever been struck as commemoratives.
Most likely no. Most British predecimal coins are no longer legal tender. The predecimal Crown was never demonetised and is still legal tender. The decimal Halfpenny, the larger pre-1990 5 Pence, the larger pre-1991 10 Pence and the larger pre-1997 50 Pence have all been demonetised and are no longer legal tender. The Commemorative 25 Pence and Five Pound (Crown) coins are legal tender, but not intended to be circulated. All other British decimal coins should be all right to spend.
A British coin.
The term "New Pence" ceased to be used on British coins in 1981. The word "Pence" should have a numeral with it to indicate how many Pence. Pence being the plural of Penny. In 1997 there would have been 50 Pence, 20 Pence, 10 Pence, 5 Pence and 2 Pence coins and a 1 Penny coin.
The British 20 Pence and 50 Pence coins are both heptagons.
All predecimal British coins have long since been withdrawn from circulation and demonetised. The decimal Half (New) Penny was demonetised in 1984. The larger pre-1990 5 Pence coins were withdrawn from circulation and demonetised in 1991. The larger pre-1991 10 Pence coins were withdrawn from circulation and demonetised in 1993. The larger pre-1997 50 Pence coins were withdrawn from circulation and demonetised in 1998. All other British "Pence" coins are still legal tender.
The 5 New Pence and 10 New Pence coins were put into circulation in 1968, three years ahead of the scheduled "D-day" of the 15th of February, 1971.
The Royal Mint advises that 94,500,300 British 20 Pence coins were issued for 2009.
There were no British 1979 20 Pence coins minted.