So we get up and put on our respective dressing gowns and slippers. (I am picturing richly embroidered black silk for Elton-me and navy blue cashmere for Zachary.) The boy turns on CBBC while I put on the kettle and apply milk to cornflakes. And then, still in our pyjamas, we spend a colourful hour discussing how blue and green make turquoise, the crucial distinction between "painting" and "scrubbing" and whether an eight-sided shape resembling a collapsing factory can, in all honesty, be described as a triangle.
It's not really much of a stretch: this is exactly the morning I spent with my own son, albeit in less luxurious textiles. It was, in its quiet and unremarkable way, a complete joy. I knew I was ready to have children when I started waking up on the mornings between Christmas and New Year, restless and bored. I didn't want to go out for brunch, or watch a repeat of Friends, or sleep until noon. I had a child-shaped gap in my life and I suspect that Elton John knows exactly what I mean.
Yet I seem to be alone in making the imaginative leap from flamboyant gay pop star famous for chartering jets, partying in powdered wigs and spending 290,000 on flowers in a single year, to dad in a dressing gown. The general consensus seems to be that John and his civil partner of 17 years, David Furnish, ordered a Christmas Day baby from the surrogacy equivalent of Amazon.com. They did so on a whim, because they thought an infant was a must-have accessory or because everybody else in their gilded circle had one. John, at 63, is also considered too old, too set in his hissy fit-throwing ways, too selfish and too self-indulgent to be a responsible parent.
A good deal of this is homophobic nastiness disguised as concern for a child. Rod Stewart, a fellow veteran of the music industry, is two years older than John. His 39-year-old wife, Penny Lancaster, is expecting their second baby in the spring and no one throws their hands up and worries how 65-year-old Stewart will combine changing nappies with the demands of following Scotland and getting his roots restreaked.
John and Furnish, 48, undoubtedly live the wildly extravagant, peripatetic life of the celebrity super-rich. In the 1997 Furnish-directed documentary, Tantrums And Tiaras, John's foot-stamping petulance and huffy nonsense - at one point he storms off a tennis court and demands a private jet to take him home because a fan has disturbed his game - is revealed in toe-curling detail. The couple's parties are legendary and their personal collection of contemporary photography is one of the largest in the world, requiring its own curator. The couple fill their many homes with fine furniture, works of art and hothouse blooms. And the staff to look after them.
None of which makes them particularly different from anyone else on the Upper A-list. Yet no-one is appalled when their heterosexual peers become parents. Apart from a few Paul McCartneyesque exceptions, the entertainment industries attract egotistical extroverts who love dressing up, showing off and getting their own way. They can't resist outrageous names and vulgar gestures. Take David and Victoria Beckham, who were married on matching thrones. Their children are Brooklyn, Romeo and Cruz. David has worn a Gucci leather biker suit, a sarong and his wife's knickers. In 2004, he was named father of the year.
Having a baby with a surrogate mother was not the first choice for Furnish and John. Last year, they tried to adopt Lev, a 14-month-old Ukranian orphan. Lev is HIV-positive, with a grim life in an institution ahead of him. Yet the Ukranian government deemed John too old. They refused to recognise his civil partnership with Furnish.
So Lev is denied a life full of orchids and picnics with Liz Hurley and discussions with his adopted fathers of the relative merits of Sebastiao Salgado and Ansel Adams. Zachary, however, will have all these things, and more. His birth, as well as earning his surrogate mother a reputed $100,000 (65,000), will create employment for nannies, mural painters (a 35,000 nursery has already been installed in the family's home in Windsor), infant nutritionists, cashmere goats and categories of professional yet to be invented to tend to his every need.
He is a very lucky little boy. He has two parents who love parties, ridiculous clothes, singing, dancing and football. With John's personal wealth estimated at 175 million, the couple will be able to enjoy parenthood without ever having to assemble an Ikea cot, pure a butternut squash or battle through Hamley's for a Ben 10 Omnitrix.
In return their son will, I hope, give Furnish and John the perspective their glittering existence so clearly lacks. John has been filling the Zachary-shaped gap in his life with booze, cocaine, binge-eating, obsessive working, raising funds for Aids charities, tennis, dogs, contemporary art and photography for most of his adult life. Now, in his seventh decade, he can potter around his many homes with his civil partner and his little boy. May he enjoy every precious minute.