Cheviot wool. Source: Classic & Modern Fabrics (book)
Part of the ‘Antique Fabrics’ series, this fabric isn’t necessarily extinct, but it was more popular in the past than the present.
Close napped, rough surfaced, wool fabric. Dense and hard-wearing, it was a popular choice for overcoats. It’s usually a twill weave, but can be plain-woven too.
Originally made from the wool of Cheviot sheep, but currently available in other types of wool and wool blends. High-end cheviot is made with worsted wool.
If you’re looking for a good-enough match, consider wool melton or a heavy tweed.