Shops like M&S no longer sell British made underwear and it is hard to find underwear that is made in the UK. However there is still some great British made underwear made. Here are a few possibilities (in no particular order) for British made underpants and swimwear:
*Kiniki (JW Walker Limited) make very good quality underwear for men and swimwear for men and women at a good price and come highly recommended. They are perhaps most famous for making tan though swimwear. Designed, manufactured and dispatched from their factory in Staffordshire, England. Each and every pair of their mens underwear & mens & womens Tan Through swimwear is made in England. However, currently all their ladies (bamboo) underwear is made in Turkey. Kinki plans that in future their womens underwear will once again be made in their factory in England, so keep an eye out for that. The Bolin razors they sell are made in England. However the socks, bags and suncare cream they sell are foreign made – http://www.kiniki.com