Ok managed to get the wheel unlocked. I could rotate it with my hand when it was on the jack. Didn't get a chance to take the drum off though was getting dark. But I took it for a short, low speed test drive around the block. There is a grinding sound coming from the wheel now. I assume that the shoes must still be touching the inside of the drum. I'll probably replace the drum though as it is very badly rusted. There was bits falling off it when I hit it with the hammer.
