I have heard it said that whistling the tune was eventually made illegal , because songs known to be nationalistic were given innocent lyrics but some contained loade words like linnet as in "She sang each note like an Irish linnet". and linnet was a naughty word. Well code for feinian supporter. Jim Maggean said it. I am sure there was a regular lexicon associated therefore. Consequently those songs were considered contentious and thereby the tune was a code to say "up yours".

Set dancing was similalry frowned on. The way I heard it was that it was danced at cross roads with musicians mouthing the music so that if the police arrived they could only cathc 1/4 of the dancers - but what if four officers arrived? A tall tale maybe.