
After two and a half days' soaking, but not shifting the mess, I had a brainwave. I got a 5c coin (eurozone), laid it flat in the bottom of the pan and slid it around with moderate pressure. Guess what - it came off like magic. Just thought it might help some other budding HFWhittingstall type with more enthusiasm than know-how.
Note to self - This method is not brilliant for use on a non-stick pan.