The first St Patrick's day parade in London was in 2002 and was entirely instigated by Americans living there. This has copied a version of American parades, with Scottish or Scottish Style pipe bands playing Scottish tunes. It is very puzzling for many of us over here to see footage from the New York St Patrick's day parade, where bands wear uniforms clearly based on those worn by the British army to express their Irish heritage.
Ironically, the first St. Patrick's Day parade in the colony of New York before the Revolution was reportedly organized by Irish soldiers in the British Army. We also know that Washington's Army observed St. Patrick's Day.

T.