As I said, the L1A1 slings, boxes and a lot of intricate spare parts such as lens housings and slipping scale drums etc etc were contracted to Cooke and Perkins (who don't exist any more) and they sub contracted the leather work to a few old ladies who were out-workers to the leather work industry. Such as Pavlova, Barrows and a few others whom I can't remember until I get my old notes out again. All of their work so far as I know was done at home and by hand. You'll also remember the 81mm Mortar tube leather cups. They did them too.
I think I mentioned it elsewhere but C&P were also contracted to supply new replacement leather Scout Regiment telecope cases but they were too difficult so it was C&P who formulated the later plastic cases that were adopted. On the strength of that I suppose, they suggested a plastic case for the L1A1 and some were produced but were far too weak and the rounded corners would collapse at the first knock.
Their logo was a CP/l\70 or whatever year it was. That's meant to be a WD arrow in the middle!
I hope that some budding future author is writing this all down