Largs Channel From Surveys by Lieutenant Comm. W.M. Passmore, R. N. Lieutenant J.M. Sharpey Schafer, R.N., H.M.S. Gulnare 1940 – 1942. . etc. . Firth of Clyde. Scotland – West Coast. (I have put the quote in based on a tube - can be less if folded).
eBay