A fair number of episodes in the history of this country are frankly best forgotten. The last thing to do with them, one might have thought, would be to memorialise them with bank holidays. Giving people in Britain a day off to mark, say, Cromwell’s harrying of Ireland in the 17th century, or the starting of the Boer War in the interest of corporate capital in the 19th, would at the very least raise eyebrows.