St George as the origin of World Book Day?

When I was in Barcelona recently I was taken on a walking tour of the city and the guide pointed out a wall carving of St George and the dragon, who is a patron saint of the city. I had always assumed that St George was a solely British icon.

The guide then told us the Spanish version of his legend;
In Barcelona there had been a large pack of dragons living there until the people fought against them until there was only one left, this dragon then lived on the outskirt of the city in a cave but over the years he became very mean and bitter and would often attack the city. The king went to talk to the dragon and asked him what was wrong, as the people were letting him live there without being killed. The dragon demanded that once a month a young girl from the city, a virgin, was to be sacrificed to the dragon for him to eat. The king agreed to this deal. However, girls realised that this was to be their fate and so soon lost their virginity to protect themselves from the dragon. The only girl left was the king's daughter as she was to save herself for her wedding night. The king desperately sends a message to the world that a dragon needs to be slayed and that the man will be rewarded. On the 23rd of April the day comes when the princess is to be sent to the dragon, she goes to the cave, however at this point a man on a white horse rides up. The man is George, the world famous dragon slayer who has come to save the princess. George slashes the dragon's throat, spilling his blood over a field, and the blood then turns into a field of roses. George picks a rose and gives it to the princess who falls in love with him and they ride of into the sunset for a happily ever after.
It became the tradition in Barcelona to always give a rose to a loved one on that day of the year, in a similar fashion to Valentine's day.
In time, tradition changed and on that day the couple would exchange gifts in the form of a rose for the woman and a book would be given to the man. The book is given to commemorate the Spanish author Miguel de Cervantes who died on the 23rd of April in 1616.
The tradition of giving a book as a gift on a certain day of the year became famous in Spain, and also came to the attention of the rest of the world. In the 1990's the UN regarded this tradition as a good way to get people more interested in books and reading, and so in 1995 the first International Book Day was celebrated on the 23rd of April. The date also coincides with the birthdays, and death days, of writers Shakespeare and Cervantes.