That's a broad arrow mark and not a C broad arrow. A British sling, looks like the M is missing. Should read M.W. & S. LTD. 1941 with broad arrow.
Nice find BTW in super shape.
Those slings were made for the P14 rifles the UK had on hand during WWII. I have a couple of those. They used to sell them in 15 packs for $5. They are good quality and durable.
All of mine have the makers name stamped in them rather than printed in ink.
Mine are marked P.I. 1940




























