Even though the lion is not an animal native to England, it’s seen as a national animal of England. What is the history of the lion as a symbol in English culture? Who decided that this strange beast from a far off land should represent England?

by brokensilence32
phil1232

This has been answered before tldr: lions were native to Europe at one time

Edit: original post by /u/lunes8

Sataniel98

Since there have already been answers concerning the origin, I'd like to point just one tiny thing out: Even though it is commonly referred to as "three lions", the animals in the Royal Arms are by heraldic rules leopards. You can see the difference clearly if you compare the English to the Bohemian arms. A leopard is striding and always looks at the viewer, while a lion is standing on its paws and looks to the heraldic right side.

jschooltiger

I wrote about this awhile back. From this older answer (OP was asking about the royal flag):

Hi Op, I'm assuming you're asking about the British royal standard -- the English flag (the cross of St. George, a red cross on a white field) doesn't have any lions on it, nor does the Union Jack. (I wrote about the Union Jack in this older post.)

Queen Elizabeth has a personal flag, which comes in two varieties. This one is used in England, overseas, and generally; this version is used in Scotland.

The three gold lions on a red field on either royal standard are the symbols of the former Kingdom of England, which existed from about the mid-10th century to 1707, when England merged with Scotland to form the nation of Great Britain. The three lions date back to the personal arms of Richard I, and have been used in various heraldic combinations with other arms over time (e.g. Edward III combined them with the fleur-de-lis to press his claim to France).

The lion of Scotland dates back to William I, and is similarly a symbol of the Scottish kingdom which ceased to exist in 1707.

Now, as to "why lions," the use of the lion as a heraldic symbol dates back to the very earliest Middle Ages. There are a bunch of previous posts on this (I'm stealing the formatting from a post from u/searocksandtrees):

In terms of lions existing in England, there were lions in the Tower of London for several centuries, though probably not continuously -- King John founded a royal menagerie sometime around 1200, and lion skulls found in the tower's moat date to as far back as 1280 or so.