Does resoling shoes on their original last make any difference?
Answer: Not in terms of actually putting a sole on the shoe, no. Putting the shoe back on the last helps reshape the shoe and take out some big wrinkles and whatnot. Other than that, you're just guaranteeing that the work is at least as good as it was when you bought the shoe. Some factories even replace the insole, cork layer, and welt.
Obviously, some cobblers are better than others, and there's some risk involved there. However given that you're in London, Justin FitzPatrick has a post dedicated to his preferred cobbler in London: http://www.theshoesnobblog.com/2013/04/my-recommended-shoe-cobbler.html
Hope this helps!
This question was first posed and answered in our Official Shoe Care Thread.
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