Procida has the same tumble of pastel houses, the same boat-speckled harbours, the same bougainvillea-draped streets as Capri – but without the crowds. The Bay of Naples’ smallest island has somehow remained off the tourist trail, bar a flurry of vacationing Neapolitans in August. Come September, the holiday-goers disappear, leaving near-empty volcanic beaches and silent old towns in their wake.