I found those keys to be common in France. People on the markets or fairs (or shoe-repairer, as most of them also duplicate keys) that work out copies of keys usually keep “blank” keys that fit NC33-1978. Actually they charge 15 euros (13 GBP) for that. I had two copie made that way, they work to satisfaction. I suspect shoe-repairer will alsothat duplicate keys ‘usually
Next time you sail to France, don’t forget market time or “cordonnier”
One last advice : put a mark on your key from outside the boat to check how long it has to enter the lock to work properly. A possible too short key was the only concern of tha locksmith on the local market. Have a nice stay in Britany, Yves.