we did the carrots and lettuce job, but always left a nice glass of Sherry outside to refresh Santa

New Year was even more bizarre. I as a ten year old and the youngest would be shoved out of the back door with a piece of coal in my hand, then have to race round to the front door and when I heard Big Ben strike midnight on the radio, would knock loudly and be let in, clutching this horrible bit of coal. Anybody know what that was to signify?? Warmth? wealth??
I think being black it signified night time??