Brian May guitar on Circles

Hi folks! Did Brian may ever played guitars on a track called "Circles"? Where can I find more informations? Thanks!

Group named Quartz, recorded in '77, bonus track on the reissue of the '04 album Stand Up and Fight; also B-side of the single Stoking the Fires of Hell (unknown release date).

...and did Brian May played guitar on this? Thanks!

Thanks Barb!