There is one big problem with living in Kensington Palace. The palace might be a magnificent example of Georgian architecture boasting numerous grand state apartments and several twee cottages, but the whole lovely lot is actually smack bang in a public park.
On three sides the palace's grounds are surrounded by Kensington Gardens, where tens of thousands of local dog walkers, commuters, runners, tourists and the occasional Australian royal writer amble past daily.
And yet, despite this, Prince George, Princess Charlotte and Prince Louis are regularly spotted out in the parts of the estate's grounds which are open to public view, including the two eldest kids whizzing about the place on their bikes.
All of this they do, safe in the knowledge that long lenses are not trained on them, nor are a horde of intrepid snappers hiding up trees or in ominous dark vans trying to take their pictures.
I'm telling you all this for a reason, trust me.
Early this morning, Kensington Palace's press outfit released a new shot of Louis to mark his third birthday, showing the little boy happily astride a red bike. (No training wheels here, no siree.)
Before we scratch this up to Kate getting bored shooting her kidlets against the bucolic backdrop of their country home, given what we know about the Cambridge tots' two-wheeler habits, the unavoidable conclusion is that the duchess just might be sending her brother-in-law Prince Harry a barbed message here.
See, last month when he and wife Meghan Duchess of Sussex sat down with TV titan Oprah Winfrey to pour their hearts out about why they turned their backs on royal life for a new shiny much, much wealthier existence in California Harry shared this particularly interesting titbit.
When Winfrey asked him what "delights" him about his new life, he said: "I guess the highlight for me is sticking [son Archie] on the back of a bicycle in his little baby seat and taking him on bike rides, which is something I was never able to do when I was young."
And that is why Kate's decision to photograph her youngest son on a bike is so marked.
Take a gander at the shots she has previously shared of all three of her little ones. While she is not averse to a prop here or there – a rope swing, teddy bear and some lovely messy finger paint – none of the kids have ever been photographed with a bike.
Which is what makes the inclusion of it so eyebrow-raising. (The image was taken on Wednesday this week by Kate before Louis' first day at nursery school.)
For one thing, there are in fact a number of shots of Harry as a child riding a two-wheeler with his own dad Prince Charles and brother Prince William. Therefore, it could be argued the duchess is highlighting that perhaps Harry has been indulging in a certain historical revisionism, something which the inhabitants of Kensington Palace did not miss.
(After all, the Sussexes' Oprah interview did include a few claims – such as that they were secretly married three days before their wedding or that Meghan's passport was taken away – that have not been borne out by the facts.)
But wait, there's more! Of a possible message, that is.
The inclusion of the bike can also be read as a very clear rejoinder on William and Kate's part that despite Harry's characterisation of the climate in the UK as "toxic", the Cambridge kids enjoy a life of relative normalcy.
In the scheme of things, Louis' red bike is a powerful symbol of the comparatively sane, press intrusion-free childhoods that royal kids in Britain enjoy today.
They all attend normal – if pricey – local schools and now for Louis, a local nursery school. George and Charlotte are seen riding on their bikes in the gardens of the palace and spotted feeding the horde of (terrifying) geese who live in the park's famous Round Pond. Were any of these public outings splashed across front pages? Nope.
Even this week, Kate, George and Charlotte were reportedly seen shopping on the nearby Kings Road in Chelsea. Have any pictures emerged? Negativo.
Sadly, little Archie faces a vastly different future.
Amazingly, within the same hour the Louis image debuted, the first paparazzi pictures of Meghan and Archie, seemingly taken on their way to or from his Montecito preschool, landed.
Leaving aside the very, very curious question of timing – I can't think of another occasion when two sets of newsworthy royal pics have both gone public within a space of about 45 minutes – it is worth noting that George, Charlotte and Louis have never, ever been papped similarly thanks to protections hammered out between the palace and Fleet Street.
The same cannot be said for the Sussexes.
Only days after the Oprah interview aired, Harry was photographed by the paparazzi looking fairly miserable as he peddled his own bike around the neighbourhood they now live in, a lurking SUV full of bodyguards trailing in his wake.
Sometimes a bike is not just a bike.
In the case of Louis and his wheels, the underlying meaning seems clear cut: That the normal things that Harry wanted – such as the opportunity for his kids to grow up without the intrusion of the media – were always within his reach. That in trading Windsor for Montecito, he was in fact giving up an excellent chance to enjoy the very same freedoms he so clearly wants for his own family.
Kensington Palace might be surrounded by public land, but the Cambridges are the most normal royal tots in history.
And in California? Archie might live on a 7.4 acre private estate replete with its own playground, but he will always face potentially being snapped whenever he steps outside the front gates. Lucky he has all that space to learn to ride his bike one day.