The British currency has never included cents.
Such a coin does not exist. The British have never issued a "cent" coin. The 5 New Pence coin was first issued in 1968.
A 20 Pence coin is a British coin worth one fifth of a British Pound (GBP). A "nickel" is a US 5 cent coin. At current exchange rates (Jan 2011), the British 20 Pence coin is worth about 32 cents USD.
A 1903 King Edward VII one cent coin is probably worth only a small amount of money. It is worth less than five dollars because it is made of copper.
It's worth 1/10 of a British Pound. You can find them in US dealers' misc foreign coin boxes for a quarter.
The one cent Euro coin is worth 0.6452 of an American cent.
A US "penny" is actually a 1 cent coin, worth 1/100 of a dollar. A British penny (the coin's official name) is worth 1/100 of a pound sterling.
Britain has never produced a 50 cent coin. The British 50 New Pence coin was first issued in 1969.
A silver 1829 5 cent coin is worth between £30 and £80
A five cent coin from 2005 is worth five cents.
In 1944, the British used Pounds, Shillings and Pence. The British have never used cents. There has never been a British 10 cent coin and the British 10 Pence coin was first issued in 1968.
50 cent
There's no such coin as a "two cent penny" because a penny is either a 1p British coin, or a 1-cent coin in the US, Canada, and several other countries. If you have a 2-cent piece with a map of Europe on one side and a picture of the Netherlands' queen on the other, it's a common circulation coin worth face value only. If you have anything else, please post a new question with the coin's date.