It was a frequent image in Celtic art and was found on Irish medieval tombs and on old copper coins.
Traditions says that St. Peter used the three leaves to teach of the three persons of the Trinity: God the Father, the Son, and the Holy Spirit.
One beautiful old Irish song says:
"There's a dear little plant that grows upon our Isle,
T'was Saint Patrick himself sure that set it;"
This writer has never found an Irish song that was not beautiful. Indeed the Irish have a gift in this regard.
It is believed that the ancient Druids honored the shamrock as sacred. They are believed to have believed that it had the power to avert evil powers.
The shamrock is a trifoil--it has three petals. The number three is significant in so many cultures that space will prohibit going further on this matter.
Because Queen Victoria hated the wearing of the green in Ireland for what it stood for many Irishmen suffered terribly by the armies of the blood-stained English throne. The Irish song, "The Wearing Of the Green" relates much of the British terror.
Since we mention the Druids please allow the writer to explain why the British are mongrels (he is one). Ancient England and Ireland had primitive man. At a point the Celts began migrating west from he Sea of Grass near the Black Sea. When they arrived on the island we call England they spread their language. The Druids fit in here somewhere but but no one is sure how at this time. After the time of Jesus Emperor Hadrian conquered Britannia (as they called the island) and the Latin language was spread by the Roman soldiers to the locals who had to deal with the Romans. Latin was the language of the Western Roman empire and Greek was the language of the Eastern Roman Empire. They also shared their genes with many young ladies there. In this regard we must note that not all the Roman soldiers were Italian but were from other conquered counties. Lots of mixed blood invaded England and left their genetic imprint there.
In 409 AD the Roman soldiers were recalled to Rome to protect it from invasion from the north. This freed Britannia to be invaded by Norsemen (such as Hagar the Horrible).
In fear and desperation Britannia sent word to Germanic tribes for help. These were the Angles, Saxons and the Jutes. These came to protect the inhabitants and soon took over the country and their early German language spread over the land. Genes, too, we are afraid.
Many hundreds of years later William the ConquererVikings from Norway so they were not true French. Then his soldiers spread their early French language and many of their genes as invading soldiers were wont to do. Even at the time of King Richard the Lion hearted there was conflict between the Saxons and the Norman French as you can read in the works of Sir Walter Scott--Ivanhoe, for instance.
From all this we have the "pure-blooded" English gentry, and the pure English language, a very challenging language to learn.