Zeri Islam

To make matters worse, the youngsters, aged nine and 10, were asked to put themselves in the place of Royal Mail staff and make up replies to children explaining why their requests for certain presents had been rejected.

One parent said: "My wife and I make a special effort to keep the belief in Santa in our daughter's mind as we believe it adds to the magic of Christmas for her and her four-year-old brother.

"What gives the school the right to decide when children should know the truth about such a harmless matter when knowing the truth does take away that little bit of magic? She'll probably figure it out soon enough anyway. But we might have had one last Christmas without her knowing if it hadn't been for the school." However, another mother, Sally Jones, 32, who has three children at the school, said she was not upset by the blunder.

"I don't think it will come as a shock to many children of that age. I think some parents fob off their children while others tell them the truth. I don't think any harm has been done," she said.

"The only advantage of Santa as a parent is that you have got someone to blame if children don't get what they want."

The Hamilton Trust, which produced the worksheet used during the lesson at Ladysmith junior school in Exeter, claimed that by the age of 10 children tended to know that Santa did not exist.

But headteacher Jackie Jackson said: "The choice of this worksheet was a genuine mistake by a teacher which we are sad about. As a school we delight in the magic of childhood and believe that Christmas is a special time. This worksheet will never be used in the school again."