Rise to the challenge of this confusing scenario with these five looks.

Receiving an invitation that reads, “smart-casual” is a bit like receiving a nebulous diagnosis from your physician. The sartorial equivalent of “It’s nothing really, but best to keep an eye on it”.

It can even trip up those men for whom designing clothing is part of their everyday vernacular. “If I’m honest, I’m not even sure what smart-casual means,” said Lanvin Homme’s creative director Mr Lucas Ossendrijver in The New York Times last year. Paradoxical but not in a pleasing surf’n’turf sort of way. No wonder even the experts struggle to pin it down.

But it’s not like MR PORTER to shun a challenge, so let’s give it a try. Maybe our Style Advice page can shed some light on the matter (if you’ll allow us to quote ourselves). “Pretty much anything smarter than a tracksuit, but less formal than a suit.” Helpful? Not really, we know. Our advice doesn’t end there, however. “An ideal answer is a blazer, white shirt, neat jeans and brown loafers.” If you want a living, breathing point of reference, take a few style notes from our Buying Director Mr Toby Bateman. He puts the “smart” into smart-casual better than any man we’ve met. “My go-to outfit includes dark washed jeans (usually Jean Shop), a Goodyear welted shoe – by George Cleverley, John Lobb or Edward Green – a white Oxford or chambray shirt and a soft structured blazer of some kind.” 

When you’re dressing for a smart-casual event, if in doubt, it’s always better to be overdressed than underdressed. And whatever you wear, your look requires balance. If you go for a jacket and pocket square, for example, ditch the tie and opt for jeans or chinos rather than suit trousers. Remember, there are few smart-casual situations where sneakers, jeans and a T-shirt will do. The key is to mix it up with something you’d consider smart.

Still not sure? Then read on for our breakdown of five catch-all scenarios. And let’s hope we never need to speak of this again.

Out of the office, but still very much “at work”? Here’s how to look as if you mean business, while loosening up a little. Start with a blazer – this one by Berluti is as elegant as any – and you have the smart box ticked from the get-go. Unless you’re a panel-show comedian (a job which necessitates teaming a jacket with a band tee and boot-cut jeans) it’s pretty hard to get things wrong from here. Avoid being the butt of your manager’s jokes and go for chinos rather than denim: Officine Generale’s seem mature without being stuffy. Loafers are too loungey, and Oxfords, too formal. Add Ami’s glossed Derbies for some laid-back finesse.

If you’re on the cultural trail, perusing art and pensively stroking your chin, you’ll want to cut a suitably creative figure. Jil Sander and minimalist colour-blocking, therefore, are your friends. Throw a bomber jacket on over the top and you’re well on your way to being part of the art cognoscenti. In appearance, at least. By using butter-soft Italian suede, Hackett brings a sophisticated edge to a classic piece, and John Lobb’s simple white sneakers elevate your jeans to stylish new levels.

If you are required to wear a suit for work, there’s a fair chance a formal shirt and perhaps a tie aren’t far from your person either. If you’re socialising with colleagues after hours, ditch both. You don’t want to be that guy who can’t switch off, even after his computer has. A contemporary Paul Smith suit with a white T-shirt underneath will tick both the work and play boxes. And why not add an understated wool sweater to proceedings? It’ll add a relaxed layer to your look.

The most exclusive gentleman’s clubs often enforce strict formal dress codes. But we’re in the business of cracking smart-casual right now, so we’re headed instead to the Soho Houses of this world, where super-smart or business-like attire is a no-no. Quite literally, if you’re wearing a tie, it’s likely you’ll be (politely) asked to remove it. As such, we’d recommend going hip and sleek with a rollneck from Tomas Maier, whose whole ethos is based on an effortlessly cool vibe paired with slim-fitting trousers and some smart penny loafers by the esteemed John Lobb.

It’s summer, so you and great aunt Ethel decide to take tea outside. You’ll need shades. Not only for their primary sun-shielding purpose, but also if last night wasn’t spent so wholesomely. Be presentable and go for a simple shirt and bookish herringbone trousers. And if the wind picks up, slip on this geometric sweater by Valentino. Additionally, it may provide some quality conversation about your aunt’s knitting projects. The Paul Smith Chelsea boots ensure you can slip seamlessly to a relaxed afternoon stroll, where you can win her over with your sparkling knowledge of bird life (of the feathered variety obviously).