William Shakespeare in 1964 was the first non-Royal to appear. Since this question appeared in the UK section, I assume you mean UK stamps.
The first gold Fifty Pound coin issued by the Royal Mint was in 1987.
There has been a British Five Pound coin on and off since 1817. The British decimal Five Pound gold bullion coin was first issued in 1980 and the Five Pound "Crown" coin was first issued in 1990. The current British Five Pound "Crown" coin is intended to be a non-circulating legal tender commemorative coin. The Royal Mint has no current plans to produce a general circulation Five Pound coin in the foreseeable future.
Such a coin does not exist. The first Quarter-Sovereign coin ever produced by the Royal Mint was minted in 2009.
The Royal Mint does not produce a "quarter" coin.
The British 20 Pence coin was first released in 1982.
No British coin has four different people on one side of the coin. It is most likely a commemorative or souvenir token celebrating 4 generations of the Royal Family.
Your coin will not be worth a huge amount because Royal commemorative coins a produced in huge quantities for release.
There was no 1978 British 25 Pence coin minted.
it was 1234 bc
Such a coin does not exist. The British One Pound coin was first issued in 1983.
Such a coin does not exist. The British 50 Pence coin was first issued in 1969.
The older design 20 Pence coin has a Crowned Double Rose on the reverse. The newer design 20 Pence coin has a part of the composite design of the British Royal Shield.