5 Shillings - Elizabeth II Coronation

I have a question about this coin
https://en.numista.com/catalogue/pieces5749.html
The Numista page explains Value5 Shillings = 1 Crown (1/4).

Is this coin is a 5 shilling coin, 1 crown coin or 1/4 crown coin .
As in India we have 100 paisa in 1 rupee we do not call it as a 100 paisa coin its simply 1 rupee coin so bit confused about this coin .

The page also explains that it is a Circulating commemorative coin , It would be great if anyone can share his experience that if someone has actually used this coin for buying something and what buying power it had in its circulating days.
How many they carry these big coin in there pocket at a time .

Pardon me if I am putting a wrong question and Thanks in advance for answering this .

1/4 of sovereign (pound)....20 shilling form a sovereign?

In the predecimal British system, there were 4 farthings to the penny, 12 pence to the shilling and 20 shillings to the pound/sovereign. Additional denominations were used for 2 shillings (=florin) and 5 shillings (=crown).

Coin denominations in non-decimal systems are registered in Numista by means of fractions of the base unit, the pound in this case. So 5 shillings = 1 crown = 1/4 pound/sovereign. A farthing is 1/960 as there are 960 farthings to the pound.

Yes to all above.

Question: Is this coin is a 5 shilling coin, 1 crown coin or 1/4 crown coin
Answer: Nearly -
Is this coin is a 5 shilling coin, 1 crown coin or 1/4 pound coin

You needed 4 of the Crown coin to make 1 pound
Crown = 1 Crown = 5 Shillings
= 5/20 Pound = 1/4 Pound
1 Pound was 20 Shillings

Nowadays the Royal Mint still make coins in that size,
but it is no longer 1/4 Pound value. They call it 'crown-sized' and
now has a 5 Pounds face value - so is 20 times more face value.