The Germans were nicknamed "the Hun" around the time of World War 1. Our Queen has German blood. Rangers have a royalist tradition. It's a bit tenuous really.
You could ask that question of a hundred Celtic fans and get a hundred different answers. Anything from the way their fans have been accused of acting like marauding 'Huns' to their tenuous relationship the the Germans 'Huns' of the Great War, ie. German protestantism (these are not my views before anyone jumps down my throat!) Some people are now trying to convince themselves that it is a sectarian insult and want the word 'hun' to be included in new legislation. To me it's no more insulting than being called a Tim because I support Celtic.
Also, just saw on the news that the Norway shooter killed 84 people in that youth camp http://www.bbc.co.uk/news/world-europe-14259356
I may have been lying, it might have something to do with a gang of irish thugs known as the Timalloys.
Has Manchester not got as big an Irish population as Liverpool? Most famous people who come out of Manchester have Irish lineage. In fact, most people with charachter who come out of north England seem to be of Irish descent. Without the Irish influx into Britain it would have the charachter of Germany. Be thankful for that Jip.