The many messages in the Duchess of Cambridge's first Caribbean tour outfit

Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge arrive at Philip S. W Goldson International Airport to start their Royal Tour of the Caribbean. Photo / Getty

And they're off. The Duke and Duchess of Cambridge kicked off their Caribbean tour this weekend, touching down in Belize for their first stop.

Kate stepped off the plane in a cobalt blue lace dress which was reminiscent of the kind of looks she wore in her early days as a working royal.

It was a new Jenny Packham design - one of her favourite labels from that time - featuring a V-neckline, collar detail and peplum waist. She teamed it with coordinating Emmy London shoes and sapphire and diamond jewellery which once belonged to Princess Diana.

As far as the couple's "charm offensive" strategy is concerned, it's a strong start: the royal blue echoes the dominant colour of the Belize flag. William, in a pale blue suit, coordinated in a way that wasn't too heavy-handed, a look which was appropriate for the climate and occasion.

This is the second time in a week that Kate has worn royal blue; she wore a Catherine Walker & Co coat and Lock & Co pillbox hat for the Commonwealth service at Westminster Abbey, a choice which is thought to have been a show of support for the Ukrainian people since Russian forces invaded their country almost four weeks ago (the Ukrainian flag is royal blue and yellow). She also wore a softer shade of blue to volunteer at the Ukrainian Cultural Centre earlier this month.

The Duchess of Cambridge touched down in Belize in the striking outfit. Photo / Getty

That jewellery, too, is significant - she wore the same pieces to meet the Ukrainian President Volodymyr Zelensky and his wife Olena Zelenska in October 2020. As an ongoing message of empathy, it's an effective one.

Sartorial diplomacy aside, that cobalt shade is very much on trend - we've been seeing glimpses of it on recent red carpets and fashion week catwalks, although it can be a difficult colour to wear without looking like you're in uniform. It's worth persevering with it though: it's one of those rare bold hues which is universally flattering - no wonder Kate has worn it countless times over the past decade.

So, whether you love Kate's look and want to try it for yourself, or you too want to reflect your support for Ukraine in your outfit, consider my guidance for wearing royal blue before you hit the shops:

My first piece of advice would be to team it with soft "off" colours, say a caramel or toffee-coloured knit or faded blue jeans. Avoid a crisp white shirt - that would be very uniform-like - or other primary hues, unless you are, very consciously, dressing for Ukraine, in which case yellow will really bring the message home.

Secondly, choose soft fabrics, which take the harsh edge off the colour: ultra-fine cashmere or flowy chiffon, for example. The lace in Kate's dress has the same effect.

The next two weeks will be demanding ones for Kate and William: their 12-day Platinum Jubilee tour - which will also take in the Bahamas and Jamaica - comes just four months after Barbados became a republic. The couple's aim, among others, will be to prevent further Caribbean nations from severing ties with the Queen.

Catherine, Duchess of Cambridge and Prince William, Duke of Cambridge arrive in a small village on the coast which is considered to be the cultural centre of the Garifuna. Photo / Getty

With that in mind, we can expect a tourdrobe rich in symbolism and homage to their hosts. Sartorial diplomacy is a delicate dance, but if there's one thing we know about Kate, it's that she very rarely puts a foot wrong.