By Charlotte Phillips

It was my "Bleak Midwinter" moment in the church that forced a carol service rethink at the school where I work. After playing a rousing piano introduction, I approached verse one with panache, assuming I'd ignited a musical flame in the congregation.

No such luck. Like the pilot light on a dodgy boiler, a few voices flickered and then died. Half a bar later, I was largely on my own as my accompaniment became an unintentional solo.

That was two years ago. We haven't attempted In the Bleak Midwinter, since.

Each year, as teachers around the country rehearse Christmas carols with the children, I can't help wondering if it's really the parents who should be having lessons. In the six years I've been doing the job, the carols that they join in with have become noticeably less challenging.

It starts at Harvest Festival. These days, Come, Ye Thankful People, Come, is a congregational non-starter. Parents under 35 just don't know it. Now parents and children sing Cauliflowers Fluffy instead.

At Christmas, it's worse. From Out of a Wood Did a Cuckoo Fly, is enough to take the average mother or father out of their comfort zone and into distant, unfamiliar territory – so we've axed that, too. It's all Starry Nights, Little Donkeys and, at a pinch, O Little Town of Bethlehem.

It is not just parents who struggle. One music undergraduate, asked to write her own carol for homework, took her tutor aside to explain that she could not as she didn't know any.

Yet until recently, parental singing power and a working knowledge of carol standards were something schools took for granted. The Holly and the Ivy, Good King Wenceslas, even the fast bits of Ding Dong Merrily, were all in the repertoire.

Parents came, they saw, they carolled. You could always count on at least one over-enthusiastic father to sing everything, including the child-only verse of Away in a Manger. Then there would be the mother whose warbling descant in the "Sing, Choirs of Angels" verse of O Come, All Ye Faithful was notable for its bravery, if not its accuracy.

Teachers also expected parents to pass on their knowledge. "We'd tell the children which carols we were going to sing and say, 'Mummy can teach you the words.' By the time the carol service came around, they were all word perfect," sighs one infant school head. It's not always ignorance that's to blame for silence in the aisles. While teachers and children are used to singing together, parents aren't. For non-church goers – and that's now the majority – being expected to perform in public is a terrifying prospect. "It's the thought of being put on the spot that's so awful," says one.

So how do I overcome parental embarrassment and achieve greater carolling confidence? Simple, say Christmas music experts. Stop clinging on to songs the parents can't sing and choose ones they can.

It's worth recognising that some carols are best left to the experts. Take my nemesis, In the Bleak Midwinter, whose irregular pattern just isn't congregation-friendly. Ding Dong Merrily, is another minefield, thanks to a chorus so fast it can sound like an experiment in mass gargling.

Caroline Redman Lusher founded Rock Choir™, whose feel-good arrangements of pop, gospel and Motown classics are proving a huge hit with its rapidly growing membership. Her tips for success are to cut down the number of verses – four is plenty – and alternate religious classics with seasonal songs. If parents enjoy singing White Christmas and Rocking Around the Christmas Tree in church, let them – as long as the vicar doesn't mind.

She also suggests that schools run carol practice not just for the children, but for their parents, too, combining mulled wine, warm-up exercises and a no-blame wrong-note culture.

So, while schools like ours can't guarantee total parental harmony during Christmas itself, we should achieve it during the carol service. As long as I keep In the Bleak Midwinter off the programme, that is.