The last 5/- 'crown' to be minted was for Charles and Diana's wedding. Therafter commemorative crown coins have had a face value of £5.
In 1969, shortly after the Battle of Britain film (starring a certain actress....) was released, the 50p coin was minted. Commonly referred to as the 'Wilson' because it had two faces and many sides..... It was also thought that the heptagonal shape was so that a suitable spanner could be made, which would make it easier to prise the coin from a Scot's hand....
In 1997 the coin was reduced in size, so that this £8 45th anniversary Elvis Tutankhamun Marilyn Monroe mosque alarm clock coin won't even be the size of the original Wilson, let alone a traditional crown.....