If the people vote "no" in a referendum and the government ignores the will of the people and tries to proceed, trials might be in order.
I don't know if you all would want to use these as symbols of your resistance, but I thought I'd just throw them out there.
http://www.gadsden.info/i/wallpaper/800x600.gif
The snake and motto can be transferred to the Union Jack, the snake could be replaced by a more British animal, and I read this motto and liked it: "Nemo me impune lacesset", which they translated as "no one wounds me with impunity."