Opinion: Young children and weddings don't mix, so why do we insist they do, asks Rachel Moore.

The Duchess of Cambridge confided to garden party guests this week that she was worried about how Prince George and Princess Charlotte would behave at her sister's wedding at the weekend.

They are two and three and will be bridesmaid and pageboy at the expensive Buckinghamshire ceremony. She's right to be anxious.

Small children and weddings are never a happy mix. Only the brave, foolish or super laid-back embrace the combination happily.

However meticulous the wedding planning, three big threats lurk to a big day's smooth-running: the weather, the couple's health (not that I've ever heard of flu stopping play at any wedding ever) and the unpredictability of small children.

Inviting little children to a wedding is like playing Russian Roulette with years of carefully-laid plans.

A tiny person's tantrum can ruin the moment. How something so small can cause so much noise, chaos and disruption appears to defy science.

But sustained screaming from a baby as the vicar leads a couple through its vows or toddlers playing boisterous hide and seek in the pews, fighting with hand-embroidered kneelers, can make it all go so wrong so quickly – and be the memory guests take away for years to come.

Two and three year olds have no real understanding of what is going on at a wedding. Why should they? They have a lifetime of sitting still quietly to come. It's unrealistic to expect they can master either.

The concept is torture - but even more painful for most parents. I say most parents, because there's always those unconcerned about their disruptive offspring's 'self expression', believing they are, and should be, the centre of everyone's attention always.

One vicar in Yorkshire even asked for the noisy child of the couple he was marrying to be removed from his church because he was making such a din.

Of course, they complained to the Church of England, rather than taking a moment to think how ridiculous they had been to expect a child still in nappies to behave like an 18-year-old just because they were getting married.

Children don't understand what a wedding is about. Being there means nothing to them, they won't remember it, don't want to be there and, thinking it through logically, involving small children in such an important, hopefully once-in-a-lifetime ceremony and celebration, is a ridiculous idea.

Ask parents what they would prefer.

Most would seize a child-free day, rather than spending it stressing about baby babble and bribing/threatening small children not to make a peep, then, when everyone else is having a great time, chasing toddlers, reading Peppa Pig, mopping baby sick off a new Phase Eight dress and taking tired crotchety toddlers home early.

Of course I mean mothers, who will be the ones missing the reception fun outside with a restless toddler or sitting in the car outside the church or ceremony venue with a inconsolable teething tot.

If there's childcare available, let them take it and enjoy the moment. If childcare is an issue, it's a guest's problem, not the marrying couple. You wouldn't blame your boss for not letting you bring your toddler to work.

Who wants their wedding to be like Disneyland, as one groom decried his?

But, stuff a couple's prerogative, who might be saving money by eliminating children from the guest list. There will always be a mumzilla who refuses to attend, on principle, because an invitation misses her children's names.

How rude to make an issue out of a decision taken for their wedding. But there will always be someone so self-centred to cause a lifelong rift because 'they didn't invite my children to their wedding.'

They take it as snub and an attack on their family. Again, almost exclusively mothers, who forget they exist in their own right and are allowed to do grown-up things without their brood that don't involve colouring pencils, a changing bag and an old grey muslin.

Those who say children are 'part of the fun' of a wedding aren't those paying the bill.

The better-off and big-hearted organise for a room and children's entertainers to avoid upsetting their parentzilla guests. Bigger fools them.

Keeping weddings child-free is not about being anti-child. It's simply reflecting that these events are not kids' birthday parties.

Invitations can never stipulate 'only well-behaved children', like the sign in cafes, 'well-behaved dogs welcome.' There's never a guarantee.

A wedding is the one time to make it all about you. Others need to get over it.