sound there is not central locking nothing fancy like thatI have just remembered but the main staelers said they would sell me a key blank and and key cutter would cut it but again I am not sure if it is the same for you as mine is much older.
Hope that is some help
stealers will charge you a fortune... hence the name. look on ebay or try paddocks for blank keys. like dopey said, you can get em cut anywhere. im assuming you still have an original? otherwise your looking at replacing the whole unit or the barrel, if they come out.
G