A folk musician friend of mine mentioned that Scottish folk music was once outlawed but I can't find any evidence that it might be true. Has the performance of music ever been outlawed or banned, specifically in the British Isles or Europe?
Much of Scottish (and particularly Highland) culture was systematically repressed by the British government after the Jacobite rebellion and the Battle of Culloden, including banning the wearing of tartan (Dress Act 1746), revoking the traditional chief's rights to dispense justice (Heritable Juristictions (Scotland) Act 1746) and the right to bear arms (Disarming Act 1746).
I've not been able to find any specific reference to the banning of Scottish folk music - the Wikipedia page on the Great Highland Bagpipe notes that
the oft-repeated claim that the Act of Proscription 1746 banned the Highland bagpipes is not substantiated by the text itself, nor by any record of any prosecutions under this act for playing or owning bagpipes.