Well, after all my questions about corking my old screw top bottles, I had a brainwave...
The bottle bank in the municipal car-park near the top of our street rarely if ever has the lids locked, so I took a load of our glass for recycling and came back with 20+ (formally corked) wine bottles!
I've soaked them in hot water and found a massive difference in the glue used on the labels:
Some floated off
Some peeled off easily
Some scrubbed off with a little effort
Then there’re the others
The ones where the glue outright refuses to come off, no mater how hot the water and no matter how hard I scrub.
Anyone have any tips for getting the awkward label-glue off of the bottles?