US President Donald Trump and First Lady Melania Trump Image Credit: AP

You will have heard of virtue signalling, whereby people post #reallyworthwhile messages about right-on causes on social media, or flash their fluorescent reusable cup in Pret, to conspicuously demonstrate their social conscience and environmental credentials.

So what is its relation, fashion signalling? At its most simple, it’s the art of saying the unsayable, or really driving your message home, via the medium of an outfit that speaks volumes. Because as much as holier-than-thou types like to claim that they just throw any old thing on in the morning — or Melania Trump’s director of communications insists that “it’s just a jacket” — what we wear really does matter. And the mattering is appreciably amplified when the eyes of the world are upon you.

Herewith, four of the most recent powerful fashion signallers...

Melania Trump

The outfit: A Burberry trench coat as she landed in Brussels.

What it’s saying: “This coat has nothing written on the back so in that sense, I am saying nothing. Having not said that, I am very excited for my trip to the UK as exhibited by the fact I am wearing the ultimate item from your quintessentially British design house. If I wear this now, I’m thinking I can get away with Dolce & Gabbana for the dinner at Blenheim Palace, right?”

The Duchess of Sussex

The outfit: An Emilia Wickstead LBD at a summer garden party in Dublin.

What it’s saying: “You’ll have heard already about how I am the Royal family’s first out-and-proud feminist and how I care deeply about women’s empowerment and period poverty. This dress shows that I am also grown-up, sympathetic, forgiving and not one for getting into catty scraps. Emilia Wickstead may have suggested that my couture wedding dress didn’t fit very well and that my bridal hair was a bit too wispy, but these things happen, so I shan’t be holding a grudge. Besides, there are only so many designers in London who make dresses as chic as this and I can’t wear Givenchy all the time.”

Pippa Matthews

The outfit: A bespoke Alessandra Rich tea dress at the christening of Prince Louis.

What it’s saying: “Don’t look at my bum, look at my neat bump... I mean, my gorgeous new nephew. You may assume that because I am now six months pregnant my wardrobe would comprise floaty empire line dresses but I am, after all, still a mega-Middleton by birth, so we don’t really compromise when it comes to maternity wear. I am demonstrating my mega-ness by wearing a very fashion-forward dress by Alessandra Rich, whose spotted designs were worn by some of the best-dressed at Meghan and Harry’s wedding. I can still play that game. And win.”

Theresa May

The outfit: A white jacket and navy shift dress.

What it’s saying: “There is really, absolutely, completely nothing to see here. I may be known for my jazzy kitten heels and love of a statement necklace but this is not a day for focusing on that, nor the fact that my Cabinet is in slight disarray. It’s about getting on with the job. Oh, and it just so happens I am completely mirroring Angela Merkel. We are the strong and stable leadership that Europe needs right now. Let’s get on with the job.”