Drive north from Porto and the city limits soon give way to a landscape of rolling hills painted green with vines. This is Portugal’s Minho province, home of a crisp, effervescent wine known as vinho verde. Everywhere you look, you’re surrounded by evidence of the region’s most famous export. But it’s not just wine being made in these hills. Sequestered away in nondescript industrial estates, you’ll find the mills and factories driving Portugal’s growing reputation as one of Europe’s premier textile producers.

Textile making has long been a way of life here. One of the world’s great colonial and seafaring powers, Portugal was a major exporter of cotton during the 18th and 19th centuries. Towards the end of the 20th century, the low price of Portuguese labour saw the industry shift towards cheap, mass-produced clothes – a trend that ended when the country joined the eurozone in 1999.

Under pressure from manufacturers in Asia and North Africa, who were able to drop prices to a level with which the Portuguese could no longer compete, they refocused their businesses on small-minimum orders, rapid fulfilment, and one thing above all: quality.

This is what drew MR PORTER here when we began the search for a manufacturing partner for our own label, Mr P. The brand is built around simple wardrobe staples: the kind of clothes distinguished not by a logo, but by how well they’re made.

The white T-shirt might be the perfect example of this. Every man owns one. Every brand sells one. It is, by design, an incredibly simple piece of clothing – perhaps the simplest that a man can wear. So, when it comes to making one that’s capable of standing out from the crowd, quality is paramount.

But what actually makes a quality T-shirt? Is it how it fits? The fabric? It isn’t immediately apparent from a picture on a phone or computer screen, which is why we took a trip to the town of Barcelos in northern Portugal to find out exactly how a Mr P. T-shirt is made.