That's a classic Balmacaan Raincoat in treated cotton. It is equivalent
to Burberry in price and quality. Because cotton is not as "waterproof"
as blends ,it has largely been replaced by the latter. I am old enough to
have worn that type of coat, but not in black. Since it is in effect "brand new"
it should be worth several hundred dollars, which is more or less what it cost 20 years ago.