The Terai hat is a version of the slouch hat worn by Gurkhas and named after the Terai region in Nepal. The Terai is made of felt with pugree wound round the crown. Pugree is the Indian word for turban and refers to the pleated hat band.
The Double Terai hat is a version of the Terai slouch hat, but with a double thickness crown and brim, designed to give extra sun protection. This hat was almost de rigour in East and Central Africa from the 1930s to 1950s.
In India, in the hills or during the cool season, the topi might be replaced with the felt terai hat, which originated with the Gurkhas and subsequently spread into other parts of the empire, particularly South and East Africa, where the double terai with its distinctive red silk lining was to be popular until the 1960s — its name, terai (the wooded swampy sub-Himalayan tract), indicating its origins.
Wearers include Frederick Selous and Stewart Granger