Of all the factories I have visited for the current book, the contrast between product and production was greatest at Zimmerli.

The production facility is a small, two-storey building in Coldrerio, a Swiss town just across the border from Como. Walking through the front door, the first thing you see is a dog-eared poster of David Beckham, wearing a Zimmerli vest. Next to it is a large photo of the Zimmerli team, taken a few years ago in front of the hills across the road. There are no more than 50 people, with the handful that have left highlighted by the snapshots of their replacements that have been glued over the top.

Upstairs are 30 women, mostly middle-aged, working at flat-bed sewing machines. Other male wearers of Zimmerli underwear, including another Beckham, and a huge Vanity Fair cover decorate the walls. The place is clean and pleasant, but distinctly lacking the glamour around the Zimmerli stock in Harrod’s and elsewhere. These are £50 pants, in some cases.

This is not the Zimmerli headquarters, which lie further north in Aarborg. That was where Pauline Zimmerli Bäurlin first started making socks for her children back in the middle of the nineteenth century. But the other local facility, the cutting room down in Mendrisio, is if anything even less glamorous. On the first floor of a warehouse in an industrial zone, the four staff slice up 20-foot lengths of cotton on an old machine that used to cut denim. The view is of a parking lot and railway lines.

None of this really matters, of course. I always say I love factories because you escape the marketing and bullsh*t of brands, their stores and their PR agencies. You can’t put a spin on a factory – this is simply how the product is made.

Zimmerli’s quality is down to the incredibly fine materials it uses, from Sea Island Cotton to incredibly lightweight Egyptian cottons. Turning from the factory visit, therefore, to my Underwear Project, of all the brands I tried Zimmerli is really the only one where the quality of the material is consistently noticeable.

That goes for some aspects of the construction as well, such as the fine single-needle seams and flat seams around parts of the underwear. The sewing machines that do that work aren’t particularly special – it’s just a question of giving more women more time to do the work.

In that way, and perhaps unsurprisingly given the cost, Zimmerli is unquestionably the best underwear I tried as part of the project. My only word of warning would be the styles, some of which can be a little old-fashioned. The Boxer-Short (252-842 in Royal Classic), for example, although it looks like a standard short, is very long in the leg and plain in design. In a thin, almost translucent cotton, that can be a little disconcerting. The shorter boxer, called a Pant (252-8851), is a good fit but surprisingly tight around the back of the leg.

There is a huge amount of variety at Zimmerli (Royal Classic alone has 12 shapes of underwear) so it shouldn’t be difficult to find a style that you like. But I recommend spending the time to do so.

Photos: Andy Barnham