I don't know if it is quite the sort of place, but there are a few leather workshops in Camden, in the stables market, might be worth asking if it's the sort of job they would tackle?? <http://redartleatheraccess.co.uk/>
Try talking to the Master Cobbler Krappy. I've recently given them a rave review for shoe repairs but I'd trust them to do a tip top job on any kind of leather accessories or garments. I'd say it's worth asking them.
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