Fred wrote:
Is there any glue or method anyone here can recommend?

Solvent polyurethanes, like "Shoe Goo" or "Barge Cement". Hard to find
and the easiest way always used to be to buy a pair of Woolies stick-on
rubber soles that included a tube.

Evo-stik 528 is about the best they do for leather, but it's not up to
shoes unless it's an easy joint to make and you can clamp it whilst
curing.