For centuries Kythnos went by another name, Thermia, after the warm springs that still run into the sea at Loutra on its north-east coast. The old name is a fair guide to the island. This is a place for bathing, long lunches and walks between villages rather than for being seen: a western Cyclades island of one working port, two inland settlements and more coves than visitors, lying between Kéa to the north and Serifos to the south.

Most visitors arrive by ferry from Lavrio on the Attic coast, with fewer sailings from Piraeus, and step off at Merichas on the west side. The harbour sets the register for what to wear in Kythnos: a curve of tavernas and fishing caïques, chairs out on the quay, nobody dressed for an audience. A linen shirt and a pair of shorts are already correct at noon, and still correct when the same table is laid for dinner. For men, the PP linen shirts in lighter colourways sit easily against the whitewash and painted shutters: a Cuba Linen Shirt in Blue, or a Laos Short Sleeve Linen Shirt in Mint Green with PP linen shorts in White.

The season runs from late May into October. July and August bring the meltemi, the dry north wind of the Aegean summer, which keeps the heat bearable but roughens the north-facing bays; on those days the sheltered west-coast coves, Episkopi and Apokrisi among them, are calmer. June and September are softer months, warm in the water and mild after dark. The island's own cheese and thyme honey are worth asking for at any taverna, eaten at tables set under a vine or a roof of cane.

Kolona is the picture most people take home: a narrow strip of sand joining the west coast to the islet of Agios Loukas, with clear water on both sides. A rough track leads close to it overland, and in high summer small boats run there from Merichas; yachts often drop anchor off it for the afternoon. This is where the PP swim shorts earn their place, in Sapphire Blue or Oyster, woven from 100% Belgian linen with a walnut button closing the back pocket. The shirt waits, folded and dry, until the swimming is over, and goes on again for the boat back to the port.

Inland the island changes character. Chora, also known as Messaria, spreads across a plateau in the north with a square of cafés, small churches and lanes whitewashed at the seams. Dryopida, further south, sits in a fold of the hills and is unusual in the Cyclades for its tiled roofs; the Katafiki cave, once worked as a mine, opens beneath it. Both villages are cooler and breezier than the coast after dark, and this is where a second layer is useful. A Male Linen Shirt in White with PP Casual Linen Trousers in Sapphire Blue is enough for dinner in Chora; on a windy night in September, a fine knit carried for the walk back to the car does the rest.

Loutra, on the north-east coast, is quieter again. Hot spring water runs from the hillside through a channel into a shallow bay, and bathers sit where the warm current meets the cooler sea; an old bathhouse stands near the shore. The dress code is swimwear and whatever goes over it for the few steps to a taverna table. For men, a PP Natural Set in Sky Blue goes on over dry skin for that walk; for women, the ladies linen set in Light Blue or Mint Green does the same over a swimsuit.

Women will find the island asks for very little beyond what the women's linen collection already holds. The Amelia linen dress shirt in Blue or Pink goes from the harbour at noon to the square in Chora at night unchanged. The PP linen blouse in Lemon with wide white trousers covers the hill path between the two villages, which is open to the wind for most of its length. Flat sandals matter more than any garment: the lanes in Dryopida are stepped and uneven.

The island's nearest neighbour is also the nearest place to see the PP collection in person. One&Only Kéa Island, a short crossing to the north, carries the garments in its resort boutique; for the island itself, see our guide to Kéa. Travelling the other way, the ferries continue south to Serifos, whose port and high Chora are covered in what to wear in Serifos.

By late September the wind usually drops, the boats to Kolona run less often, and the sandbar is left to whoever walks out to it. The springs at Loutra run warm in every season.

Read more: What to Wear in Sifnos  ·  What to Wear in Mykonos