1922 Garda Communications System

"This is what my Grandad used to attract attention or inform people of the police presence! People under 25 years of age may not remember a time when there were no mobile phones or 2 way radios! The whistle us engraved "The Metropolitan GÁRDA SIOCHÁNA" and the "CH" of SIOCHANA is represented by a T then C. I remember learning something about that in school but now even on a Google search I can't get information on why CH was spelt/ written this way. The whistle was made in Birmingham by " J Hudson & Co" patent 5727 Two piece top (1908) . "The Metropolitan" possibly refers to the whistle model. On the key chain is a silver button which is hallmarked. "