Francisco has just mailed me a scan of this photograph. As you can see, it is a publicity photograph to promote the release of “Theme from M*A*S*H”, which he released as a single in 1980. We presume the photograph dates from the same year.
Theme from M*A*S*H, and its B-side Shimmering Harp, can both be found on the album Shimmering Harp, available in the store.