There's a pageant each year, I think, during which people dress in Civil War period costumes. I've been in the Man and Scythe when everybody but myself and my friend was dressed as such; it was a mildly psychedelic experience, I tell ya. This would, obviously be a great photo opportunity if somebody wished to do the job and send the results to the gent mentioned in the OP.
I believe it happens some time around the end of September or early October but couldn't be sure. I'm rarely sure of anything related to my visits to the Man and Scythe - it's the cider, you see. Does that period coincide with the date of the massacre, maybe?
If anyone's keen to know, I could get in touch with my parents to see if they know when it is; they still live in Bolton.