Dookie the dog is kept well away.

Dear Lilibet and Margaret are getting so excited, desperate to write their letters to Father Christmas.

You remember that the Duchess always takes them to Harrods to have a look at what they might like to add to their list? (Not that they are spoilt – not at all!) This year, the Duchess invited me to join them because Alah, who usually goes, had a dreadful cold. I have walked past it many times but always been a little intimidated by the sheer size and glamour of it. And now, to be driven up, sitting next to the Duchess, and have one of the green liveried doormen help us out and into the shop, was wonderful.

The shop was closed and we were the only customers. Can you imagine?

It smelt of leather and perfume and it was all lit up and so warm. Our small party was taken up in one of the many lifts to the fourth floor. The Princesses giggled all the way and, when the door opened, we were in the toy department – an Aladdin’s cave filled with the smallest bag of marbles to a mini replica of King George’s Rolls-Royce Phantom. The girls were each allowed to sit in it and pedal around the department. When they had done that, they took little notebooks and pencils out of their small bags and began making a list.

Lilibet fell for a small farm with stables and fences to make two fields. ‘Look, Mummy. And it has two horses and little jumps to go over.’ The Duchess told her to write it in her book, and that if Father Christmas thought she had been good, perhaps she might receive it for Christmas.

‘When I’m grown up,’ Lilibet told me, ‘I am going to get married, live in the country and have lots of horses, dogs and children.’

Of course Margaret found the dressing-up clothes and immediately wanted the most sparkly fairy dress with a wand and a tiara. ‘I have been good, Mummy. I have.’

The Duchess was so good with them, making sure everything was written down and no promises made.

After they had finished their lists, we were taken down to do a bit of shopping ourselves. The Duchess was interested in gloves as gifts for her friends and I bought you and Dad a Harrods souvenir. But that is the only hint I shall give you!

The next day, feeling like Cinderella after the ball, I took the Princesses to Woolworths to buy their presents for the family. This time we shared the shop with many customers but the little girls were very good at not drawing attention to themselves. I think, with the detective in tow, we looked like any other family.

It was so sweet to watch them choosing small trinkets for their grandparents: a scrapbook for the King to put his stamps in, and a small china posy of violets for the Queen. Then they picked out a brooch fashioned like a dog for the Duchess and a hand fork and trowel set for the Duke. (Although I think Dad has a better one!)