The shocking assertion was contained in a worksheet which asked the children to compose a Christmas letter.

The worksheet handed to the Year 5 pupils said “many small children believe in Santa” but that his letters were actually handled by an official at the Post Office.

To make matters worse, the pupils were then asked to compose a reply to one of the “small children” explaining why a request for presents was being turned down.

But the main explaining had to be done when the children went home. Their parents, some unbelievers themselves, had to explain why not everything that you are taught in school may be true.

Jackie Jackson, the head teacher of Ladysmith Junior School, Exeter, has written to parents to apologise. She said that the class teacher had downloaded the worksheet in error from an educational resources website.

She said: “The choice of this worksheet was a genuine mistake by a teacher, which we are very sad about. Having three children myself, I understand how parents feel.

“The last thing we wanted to do was take away the positive and magical side of Christmas and I have wished all the families a happy time.

“I have apologised to the parents and this worksheet will never be used in the school again.”

The apology came after a complaint by the parents of one nine-year-old pupil. The child’s father 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 takes away that little bit of magic?” Other parents with children at the 490-pupil school agreed. Sam Horn, 28, whose children, Charlotte, 6, and Kieron, 8, believe in Father Christmas, said it was up to parents to discuss with a child whether he is real.

“Kids grow up too quickly these days. Children should have the right to stay innocent for as long as possible. Teachers don’t have the right to decide these things.”

Another parent said that her child had brought the worksheet home with her. “When I saw it I instantly realised what it meant. It is not up to anyone apart from the parent. I have received no apology. The damage is done.”

Some unbelieving parents were less concerned. Sally Jones, 32, said her children Cory, 10, James, 8, and Tasha, 6, knew “the truth” about Father Christmas. “I don’t think it will come as a shock to many children of that age,” she said. “I don’t think any harm has been done.

“Children don’t care as long as they get what they want for Christmas. The only advantage of Santa for a parent is that you’ve got someone to blame if children don’t get what they want.”

A spokesman for the Department for Education and Skills said that there was no official policy on Father Christmas and it was up to individual schools to decide what to tell pupils.

Leaving a glimmer of hope for those of us still expecting a visit, he added that the DfES was not able to comment on the existence or otherwise of Father Christmas.

Is it important for kids to believe in Father Christmas for as long as possible? Do your children still believe he exists? Tell us your views

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