If you ask me, it is time I gave Kate Middleton my advice on marrying a royal who will one day become King. It is good advice and it is sound advice, as handed down through the generations, and if she follows these tips she will have a most happy marriage:

* Don't summon the doctor should William ever call for his pipe and his fiddlers three in the middle of the night. Chances are, he is just being a merry old soul, for which there is no treatment.

* Sometimes, accidents happen. For example, if an egg-shaped being with spindly limbs were to fall off a nearby wall, you could order your husband to send all his horses and all his men, but it won't do any good. Have a cry, love, then move on.

* Should you bake some tarts, all on a summer's day, you'd do well to keep a close eye on all passing knaves. I hate to sound knavist, and I'm not – my fishmonger is a knave and he has never diddled me – but some can have nasty dispositions. However, as this is a seasonal problem, you can bake tarts all on a winter's day and they are perfectly safe to leave, so freeing you up to go shopping, have your hair done or order some beheadings. (John Lewis do good beheadings, as do Harrods, although they are pricier).

* Beware of any pies served in the counting house – between the ballroom and library; ext 5678 – and always stand at a safe distance when it is first cut. Live birds may fly out and if I had to hazard a guess at how many there would be, I'd say four and twenty.

* You may try to tempt your husband with all sorts of fancy spreads and Bonne Maman preserves, but the fact is he likes a little bit of butter on his bread, and that's that. It's a small thing, but if you keep this in mind, you'll save yourself and your dairy maid much to-ing and fro-ing over the years.

* A cat may always look at you. It's just the way it is.

* If your brother-in-law, Harry, insists on marching ten thousand men up a hill, down it, and then up it again, leave him to it. He has always been daft in the head and, this, at least, keeps him busy and amused.

* Should William ever show any inclination to trade his kingdom for a horse, tell him to stop being a big silly and to come inside right now, before it gets dark. You must be quite strict about this. A kingdom for a horse? Nuts!