When celebrity clients want advice about anything from red-carpet, social and child-rearing etiquette to how to take tea with royalty, it’s Lisa Gaché they turn to.

Indeed her 2014 book, Beverly Hills Manners: Golden Rules from the World’s Most Glamorous Zip Code, has become something of an etiquette bible out there and if anyone knows what lies in store for Lilibet ‘Lili’ Diana Mountbatten-Windsor’s first year, it is her.

“In LA, celebrities are assured two things when they have a baby: privacy and control. And let’s not forget that in Hollywood celebrities are our royalty, so royal celebrities are in a sphere of their own. Which means that from the moment she arrived, right through her early months and years, Harry and Meghan will be able to control the narrative for their daughter.”

So what does Lili’s La La-tastic first year look like? Well, she’s come into the world under very different circumstances to the royal births we’re used to witnessing in the UK, says Gaché.

Emphasis on “witnessing”. Not for Meghan the gruelling new mum press hazing Princess Diana, the Duchess of York and the Duchess of Cambridge were forced to go through as they posed for their photo-calls outside the Portland’s Lindo Wing hours after giving birth.

The Duke and Duchess of Sussex with their son Archie

Credit:  Toby Melville/Reuters

Gaché says “with the very best doctors on hand, and the privacy that affords them meant that they were able to announce their baby girl’s name when they were ready, rather than having it leaked by hospital staff. Because despite the Non-Disclosure Agreements, details can all too often filter out before mother and baby have even been discharged.”

Any more information beyond her name will be guarded stringently, the social commentator insists, “until her parents are ready to divulge it”. And I can’t help but picture Winfrey, who is already Baby Sussex’s godmother in all but name, announcing more details to the world’s press.

Then comes that all important “Madonna and child” first photo, “which again, Meghan won’t want taken until she’s feeling her best”, explains Gaché, “so it’s likely to come out within the first two weeks rather than the first few days”. 

Those first weeks will be made easier by the elite baby-rearing SWAT team every LA mum has in place from the moment of conception. Like film stars, these celebrities in their own right are known simply by their first names (“You’re going to have to call in Donna”) and will fly from coast to coast to wean and sleep-train your baby.

“Currently ‘the Happy Sleeper’ method is most in vogue,” Gaché tells me.

“It was founded by two psychotherapists and sleep experts, Heather Turgeon and Julie Wright, and is based around neurological development and the idea that babies are not ready to be sleep trained until they are five months old at the earliest.

Baby paraphernalia has always been comically ethical and progressive in LA, and for Meghan and Harry, only the woke-ist of the woke will do. And it doesn’t come cheap either, like the Snoo sleep training bassinet celebrity sprogs are currently swearing by, according to Gaché.

Developed by legendary American sleep guru, Dr Harvey Karp, the coveted Snoo rocks with the same gentle rhythm the baby was used to in utero, has sounds to match, a “weaning into the crib” feature and is controlled remotely your phone. But at $1,295, that bassinet had better be able to read Baby Sussex a goodnight story into the bargain.

Meghan has authored The Bench, a book inspired by her husband and son

Markle’s new children’s book, The Bench – “the heart-warming tale of a special bond between a father and his son through the eyes of a mother” – is just one of the books “Lili” Diana is likely to have on her nightstand. And with a number of classics now considered “off-message” if not downright evil, “there’s a whole new collection of books out there teaching kids from age 0 to think the ‘right’ way,” says Gaché.

Ibram X. Kendi’s Antiracist Baby is a favourite in LA, along with Cat Stevens’ Peace Train, “which celebrates hope, love, and the celebration of all cultures and identities”.

And although Dr. Seuss may have been cancelled (something about racist caricatures and abject green eggs and ham-ism) The Lorax is apparently still allowed, “because it chronicles the environment”.

That love of the environment will be honed, alongside motor skills, at the baby class of the moment: Wild Child. “A boutique children’s play space encompassing California cool with a distinct Hawaiian vibe”, Wild Child “is inspired by the belief that a child’s environment acts as a teacher". Amen to that.

And although on the East Coast babies are more likely to be expected to recite the Mandarin alphabet and identify Cézanne’s Bay of Marseilles on a flash card by the age of one, “out in LA – at least for the clients seeking my expertise – the emphasis is more on getting them to master kindness, courtesy, respect, consideration, and ethical behaviour”, explains Gaché.

All of which means that by the time Lilibet Diana hits that milestone, she is likely to have a higher social conscience, deeper understanding of sustainability and be an all ’round Better Person than most British adults. Which is an achievement well worth celebrating.

“And in LA, the 1st birthday is enormous – epic,” says Gaché with a chuckle. “In fact it can cost more than some colleges”.

But don’t worry: the cake will be vegan, the decorations sustainably sourced and the birthday girl dressed from head to toe in avocado skin and hemp-blend biodegradable clothing sustainably sourced in Perú.

We won’t expect an invite, but I think we will be able to count on Winfrey delivering the details of that “very private day” in a two-hour special.