Check Wolsey. Expedition collection. As in Scott. Antarctic.Wolsey can lay claim to being one of the oldest textile firms in the world (est. 1775) with very British knitwear and non-exciting undergarments as their mainstays. They are currently owned by Matalan.
Wolsey was one of the outfitters that clothed R.F. Scott and co. and they (Wolsey...) have dug through the archives and recreated some of that kit. Some items are trumpeted as being Made In England or similar, so I will assume the rest made in Thailand by robots -all prices are v v reasonable.