My son's big blue eyes were wet with tears, his bottom lip trembling. 'What is it darling, what's happened?' I asked, clutching his hand as we made our way out of the school gates.
He took a deep breath, his voice choking with sobs. 'Michael said Santa Claus isn't real,' he cried. 'He said your Mummy and Daddy deliver all the presents.'
I bit my lip, and tried not to panic. Michael had a big brother who took great delight in giving small kids the facts of life. Under normal circumstances it would have been an opportune moment to admit that yes, the man with the white beard and red hat isn't real, and that logistically, it would be impossible for him to bring sacks of presents to every child in the world in the space of 24 hours.
But I couldn't tell him the truth. Because as a special once-in-a-lifetime treat we'd booked a trip to take him to Lapland that Christmas to meet the real deal - or as near as dammit.
So I took a deep breath, and I did what I felt was right in that situation. 'Santa Claus IS real,' I told my son. Then (and this is the worst bit): 'He just doesn't go to Michael's house.'
Of course I felt guilty, but what else could I do? And it was worth it a few weeks later when we flew to snow-clad Finland. My little boy loved the snowmobile rides, the husky sledging and the drinking warm blackcurrant in a teepee (!). But the highlight of the trip was the moment we were led through the silent dark forest to a hut filled with presents. There was a log fire in one corner, and in the other, the most genuine looking Santa I've ever seen in my life. His cheeks were fat and red, his beard was real, his belly shook like a big bowl of jelly, the works. Even I started to believe, and the look of sheer wonderment on my son's face was priceless. It was a truly magical moment, one that brought tears to my eyes then and now.
He's much bigger now, but the other day I asked him if he could remember when he found out Santa Claus wasn't real. 'Yes,' he said. 'It was when Michael told me.' 'You knew,' I gasped. 'You knew all the time when we were in Lapland, and you didn't say a thing?' 'Well,' he shrugged. 'I didn't want to disappoint you.'