Need Help With A Dragon Slayer Coin.

That's a bit vague - do you have a picture?

The "guy on a horse" is Saint George. The design on the Victoria crowns is the same design that was used on the gold sovereigns, designed by Benedetto Pistrucci. There was a crown in 1951 with the same design, but otherwise the design was primarily used on the gold coinage. There was another version in 1935 which also depicted St George, but in a stylized Art Deco theme. The silver crowns with the classic Pistricci design were only struck in Britain, the gold coins were struck in numerous mints throughout the Empire, in Australia, Canada, India and South Africa, as well as in Britain itself.

The 1951 Crown was cupro nickel,the 1935 50% silver and before that sterling silver.Gold sovereigns are still struck with the
Pistricci design as well as some other large gold denominations.There is also a sterling silver £20 coin recently struck.
The Royal Mint offered these at face value...in fact if you bought 3 they were £60 delivered.

Thanks.

I should have mentioned, the coin I posted is a

1890 Great Britain crown