I hadn't heard about it either until it came up on a podcast that I listen to.
Here's a short(ish) discussion: http://www.ghost-story.co.uk/index.php/poltergiests/273-the-black-monk-of-pontefract-yorkshire-uk

And here's a link to the podcast: https://www.astonishinglegends.com/al-podcasts/2018/09/08/ep-117-the-black-monk-of-pontefract-part-1

I highly recommend that podcast if you're into paranormal stuff. Especially the early episodes.