The sarong is no longer in purdah in Sri Lanka.
For Anglicised Sri Lankan men, who comprise the majority of the country´s professional, business, social and political elite, the sarong has long been "home clothes". Most of them sleep at night in sarongs and lounge around in the house in one. But it is simply not done to leave home for business or pleasure clad in anything but trousers and shirt.
For formal occasions like weddings, the favoured attire is a western-style suit with jacket and tie despite the heat and discomfort. Young executives and not-so-young public servants favour shirt and tie for work, with the St Michael´s brand from Marks and Spencer particularly favoured. The less affluent with no air conditioning at work by grace of either taxpayer or shareholder will sport open necks for reasons of comfort/convenience/economy. But out of home, it is still trousers for most English speakers.
In recent years things have been changing and a few, very few, are venturing out of their homes in sarongs. The late President Ranasinghe Premadasa who was never seen in trousers after entering public life favoured a white sarong for regular wear. A sarong and shirt were his "smart casuals". His predecessor J.R. Jayewardene, who relaxes at home in trousers and bush shirt, also opted for the national dress in public during his several decades of political life.