Sounds like the liners have become stuck to the drum. I have had this problem when I leave my car for a long period with the hand brake on. I usually have to pull the drum off and put it back on again. The hand brake may look released but the liners are still stuck. Sometimes gentle rolling back and forth releases it but usually means the drum has to come off and cleaned up! I now leave the hand brake released.
Wasn’t I supposed to come and see the car? (Monmouth??)
Work gets in the way of everything. I have a drum puller but am out of the UK for the next two weeks…