This 1965 Collins edition with illustrations by Robert Stewart Sherriffs is a reprint, with the original seemingly from 1947. It looks like a reprint of the same line as this 1979 edition
It has a beautiful leather cover and comes with a case. My copy has plastic protective jacket over the cover. I took it off for some of the photos.
Update 09/2023: Updated the layout, tweaked page copy, added more pictures.
The artwork by Sherriffs is simply stunning. So bold. Some of the most distinctive illustrations for a Rubaiyat that I have ever seen.