Black Friday as a commercial phenomenon doesn't really exist in the UK ([1], [2], [3]), although some in marketing would like you to think otherwise. The event is considered more acceptable stateside, in part because it's been tied to the day after Thanksgiving: an event which isn't commonly celebrated outside the USA.
In the UK, "Black Friday" can refer to a number of important political and social events, including those commemorated on the following dates:
- 31 January: Battle of George Square, Glasgow, in which many people, including women and children, were injured owing in part to an unprovoked baton charge by police.
- 14 October: Eyemouth disaster, in which 189 fishermen died.
- 18 November: Women's Suffrage Protest, in which 200 women were assaulted by police.
While these are all far more interesting and worth remembering than a commercially organized shopping marathon, none of them occurs on this day either. There are also many more "Black Fridays" listed on Wikipedia if you'd like to read further, but we don't consider them here.