“This is the test,” she declared triumphantly five minutes later. “If Santa Claus is real, that miniature TV for Pounds 149 will be in my stocking. ”

Did she still desperately want to believe it, and were her tastes soaring towards the Porsche bracket? Or did she know it was untrue, but was skilfully blackmailing me into a last-gasp effort to preserve for one more Christmas the precious dream - aware of our miserable adult guilt at smashing it?

Seven or eight is a watershed for so many primary school parents. Ominously, they wait for the day their kid comes home with anxious face and fidgety feet: “We were all talking about Santa Claus at break and Julia says the parents do it.” I still vividly recall my own rude awakening by toothy Linda with the scrubbed pink face in Inverurie school: “It’s jist the parents,” she squawked to the shocked gaggle in the girls’ cloakroom .

I thought I’d be hugely relieved when Rowan asked the dread question before Christmas. “Never again, thank God, never again,” I breathed a year ago, tiptoeing in terror in and out of the dark bedroom with rustly stockings for her and about seven rag dolls, aghast at the prospect of eyes opening in shocked betrayal. “Next time she’ll know.”

But I still felt terrible, and still made excuses in an attempt to break the news gradually. There is a Saint Nicholas up in heaven, I warbled, but he can’t look after children without parents helping him out. “Oh, you disappoint me,” she sighed with heartbreaking restraint and adult composure, and changed the subject. I thought that was that - but this time we still went through the charade again, and she accepted the Game Boy in exchange for the camcorder. Perhaps she kept her eyes shut tight as I rustled the stockings, out of the considerate wish not to embarrass me - but who knows? Other parents said their own kids were still struggling with belief and disbelief, changing their minds and hopes each week as stocking-night approached.

This watershed always raises the age-old dilemma about deceiving one’s children. Is it justified, even for the best motives? Do the years of innocent pleasure make it worthwhile - or do they never forget this first betrayal? I don’t know the answer, but I do know adults need to take far more responsibility for the fantasies of children.

Children are often very practical and down-to-earth, yet it is their fantasies which are emphasised and held against them, branding them unreliable by nature. They carry a health warning: take their truth with a pinch of salt. This is seen most starkly in endless child abuse cases. Respectable adults couldn’t be fibbing, the kids have imagined it, lied about it, or watched too many videos.

Yet case after case in the media has proved up to 20 years later that it was small people who spoke the truth, and those trusted to keep them safe (often, and sadly, in schools and residential care) who were spinning a tale.

It’s time we admitted most child fantasies are deliberately implanted by adults from the youngest age: fairy stories, cartoons of animals as talking people, sci-fi TV and computer games, Daleks and monsters, bogeymen, friendly ghosts and Father Christmas. It’s usually from well-meaning motives - but can we really wonder that children grow so confused?

It’s a more alarming challenge to adults when children raise the subversive possibility of grown-up fantasy. “How do you know God exists?” Rowan demands after a heavy school day. “You could be quite wrong.

“My friends and I have been discussing this at school,” she continues calmly, “and we have different opinions. If he exists he wouldn’t let so many bad things happen surely. Anyway, have you seen him?” Why couldn’t these wretched children have stuck to their avid discussions of Father Christmas? At least the difficult questions about Santa Claus will eventually go away. The difficult others, one suspects, will run and run without limit of time.

Sarah Nelson