Do not know this unit but assume it is the old rewirable fuses. Wylex may still make them. If you have tried local electrician suppliers most electricians will probably have a few they have taken out.
However if you are after consumer unit fuses similar to plug fuses but bigger QVS do them but not sure if Screwfix do (Both on internet).
Why no dump them and go for modern MCB in a nice new consumer unit?
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