ISO 646-GB
From Just Solve the File Format Problem
ISO 646-GB (646-GB, ISO IR-4, IR-4) is one of several 7-bit character encodings in the ISO/IEC 646 series which are national variants, replacing some of the ASCII characters with other characters suitable for particular languages. This one is aimed at the British market. It replaces the ASCII # character (23 hex) with a British pound sign. To maximize confusion, Americans sometimes refer to the # sign as "pound".