Its been a while since I heard this rhyme.
The lion and the unicorn were fighting for the crown; the lion beat the unicorn all round the town.
Some gave them white bread, and some gave them brown; some gave them plum cake and drummed them out of town.
During the Tudor period the supporters, the creatures holding up the shield or helm, for royal heraldry tended to be the white hound of Richmond and the Tudor dragon. It wasn’t really that much earlier that supporters had made their presence felt. It’s usually agreed that King Henry VI was the first king to use heraldic supporters in the form of two antelopes. Prior to that kings used badges (e.g. Richard II and his rather famous white hart) but they weren’t officially there to support the royal coat of arms. The English monarchy frequently used the king of the beasts on its heraldry either on the standard or as a supporter.
The unicorn is straight forward. It first made its appearance when James VI of Scotland became James I of England. The Scottish coat of arms was supported by two unicorns usually in chains because a free unicorn is a particularly fearsome beast. Having said that Mary Queen of Scots used lions on her privy seal and other folk used unicorns because of their many virtues and links to Christ.
In order to symbolise the union of the two kingdoms James combined the coats of arms and merged the supporters, the Tudor dragon was removed and the Stuart unicorn inserted. In reality, of course, the merger wasn’t necessarily that friendly – think of Edward I and the virtually constant warfare between the English and the Scots during the thirteenth century and fourteenth centuries. The borders between England and Scotland had their own laws because the wars turned into sporadic raiding and feuding. James may have abolished the marches and the wardenry (who controlled the lawless borderers with their own brand of violence) saying that from henceforth the borders would be known as the ‘middle shires’ and merged his heraldic supporters but it didn’t do a great deal of good in the long term -certainly not to the monarchy, just look at the role of the Scots during the English Civil War. And of course in 1715 and 1745 the lion and the unicorn really were fighting for the crown when James Stuart and son tried to reclaim the crown from the House of Hanover. Hence the nursery rhyme which dates to the seventeenth century. Albert Jack in his book Pop Goes the Weasel suggests that the verse about bread and cake is about the populace’s support of James Stuart a.k.a. The Young Pretender or Bonnie Prince Charlie during his campaign as far as Derby.
I think there may be another verse about being beaten three times but I’m not absolutely sure. These particular specimens come from Holyrood House.