Help in dating a Royal Signals black (very dark blue) beret

[zorgon]

I recently acquired this Officer’s black beret with provenance to Royal Signals but I don’t know the period of issue as I would like to match up the age-appropriate bullion patch. From the photos below, can anyone offer an opinion?
The original label from the inside center was removed at some point and the owner did write his name over the spot. A few faint letters remain of the "Kangol" sticker label. Out an abundance of caution and to protect his privacy (although it may not matter), I've blacked out the previous owners name. I'll pick up a bullion badge, contemporary to the beret once I date it. Fortunately, they don't appear to be expensive. I hope I've hit the highlight aspects of construction that one would need to narrow down a date. There are no other labels or inscriptions. It weighs about 100 gm if that's any help. I would assume the stitching pattern of the headband will give considerable information as will the buckram design to those in the know.