The Framers Forum

Has anyone seen this T hinging technique before? The label is from an "FATG Commended Framer" from central London C.1980's/90's.
Just wondering if this was once a thing. The hinges appear to be self adhesive cotton.

Also interesting is that the mount is in surprisingly good condition and although the bevel is slightly discoloured in the centre between the face sheets, it is a lot lighter colour than I was expecting. The backing board is some kind of pulp board.