Not a clue in Diss but just may be worth checking out your nearest J&S etc. Tanya at J&S Doncaster gave me the number of a lady who makes appt with you then comes into store, measures you n takes your leathers to make them fit properly, she then brings them back to store n checks they are a good fit. She also does repairs. Could be worth a try!
Failing that check out local cobblers. The one in the village does leatherwork and regularly has full leathers, trousers n jackets hung up awaiting collection. I know Stu took one of his sports bike boots for a zip replacing. Came back, couldn't tell it wasn't the original one 👍
I'm planning to send my Lewis Leathers Monza jacket to these people for repairs. They seem to have a good reputation, so I'll let you know how I get on with them. http://www.bysonleather.co.uk/index.htm