6710 TPS Printed and made by Garrod & Lofthouse Ltd. Patents pending T20956/ST20956, as printed on bottom of rear sleeve, scan #41518. That 6710 code is same as Oct 67, the month of original release.
I had the luxury of comparing a huge scan of same LP at (2848 x 2136) size, on flickr.
Note: the scan I read from is off of the mono version, but the sleeve is made up of two parts, front laminated, with 3 flip back 'ears' plus an un-laminated monochrome back sheet.
The information on the front colour printed and laminated portion being the same, it is used for both variants.
The front photograph I checked does not carry stereo or mono ID.
Alternative (later?) back sleeve and labels added.
Matrix side 1 (image 68606) = ST1 20956-1 and 1 and GP (machine stamped).
Matrix side 2 (image 68607) = ST2 20956-1 and 1 and RO (machine stamped).