Welcome to the wonderful world of being a family of five, writesa mum who has been there, done that but probably can't find the tee-shirt under a mountain of laundry

It is just possible that Kate already has access to plenty of parenting advice. And as the eldest of three siblings, she has been part of a family of five for most of her life. But she's only been a mum-of-three for a matter of days and with almost 19 years mum-of-three experience, plus I've failed to knit anything for the baby prince, I am delighted to offer these tips to the Duchess.

1 Down with democracy

When there are three children and two adults there is absolutely no point in allowing anything to go to a vote. From 'What shall we have for tea?' to 'Where shall we go on holiday,' ice cream, doughnuts and Disneyland will always win over fish pie and Devon.

2 Label them (part 1)

No, not to remember their names, there are not that many of them, yet. But childcare experts frown on labelling your children 'the forgetful one,' 'the greedy one,' 'the silly one,' the anxious first, the awkward middle, the spoilt youngest etc. If only I'd worked out earlier that if these child psychologists are right then I could have labelled mine at birth the rich one, the happy one and the generous-one-who-loves-nothing-better-than-making-sure-dear-old-mum-is-looked-after-like-a-queen, and lo, it would have come to pass. (Kate, as a future actual queen, might not even have to try very hard with that.)

3 Label them (part 2)

Actually, you might need to label them to remember their names. I am renowned for addressing each of my offspring with a string of names belonging to their siblings, father, friends, the pets of random strangers, before finally remembering the real name we spent countless hours choosing. You have already missed a trick, Kate, by not calling the baby born on St George's Day after his elder brother George. Then you would have a chance of at least getting the boys' names right.

4 Hand-me-downs

Your daughter will definitely not remember and resent it for ever if you insist on red rather than pink wellies so they can ultimately be handed down to her brother. Oh no, that will certainly not be recalled more than 20 years later. Again, Kate is already brilliant at re-using stuff. Not only has she been spotted in the same maternity coat during different pregnancies, but Prince George and Princess Charlotte regularly appear in public in outfits handed down from Edwardian times.

5 It's not fair

I loathe the retort 'Life's not fair.' It's whiny and unhelpful and true. Give up on trying to be fair. You simply won't remember how much pocket money, birthday money, university money, dukedoms etc you gave the first one. And with one destined to be monarch and the others born to backfill the Buck House balcony, the problem is compounded (but maybe alleviated by a couple more dukedoms etc.)

6 You won't necessarily need a bigger palace

When we worked out our house had two fewer bedrooms than people, we got creative. After several years of kids sharing rooms we reconfigured the bathroom and carved out an extra bedroom, aka bed/room, as once the bed was in there wasn't really any room. A friend with four children took inspiration from Harry Potter and converted an under-stairs cupboard into her own sleeping space. Magical it was not. But fear not, Kate and Will, if you find you have too few palaces, you are always welcome to return to Anmer on the Sandringham estate.

7 No pictures

The royals are understandably protective of their children's privacy. But with many parents-of-three admitting they had basically stopped paying attention by the time baby number three arrived, Kate and Will might be glad of people's pictures. While there will be palaces full of pictures of George and Charlotte and their first smile, tooth, steps, etc they might find they can barely muster the energy to get off Facebook and raise a phone to snap baby number three.

8 Label your photographs

When my children were born, in the olden days, we still used cameras to take pictures, and then had them developed, and then (occasionally) put them into physical, not digital, photo albums or (usually) left them hanging around in physical, not digital, folders until moving them into drawers and old shoe boxes for that fabled day in the far distant future when we'd have time to sort them out. The children in question are now all old enough to vote (in local and national elections rather than on what to have for dinner or where to go on holiday, obvs) but the photographs remain unsorted and I'm not entirely sure which uniquely beautiful baby is which.

9 Hands up

With two children at hand-holding stage you have a parent for each, or a hand for each. With three you have a hand for two of them and must then control the other one by yelling and bribery. You'll also need to add several years to everything you allow your first to do, because after the oldest has fought all the battles about going shopping without an adult, having ears pierced, staying out all night, taking charge of their own country, it is the law that subsequent children reap those benefits several years younger.

10 Relax

By the time you have three children, your eldest has watched you attempt to bring up the middle one and can step in to find the youngest food, clothes, Peppa Pig on the telly... The baby might eventually mention it's like having more than one mum, which can only be a delight.