At a cost - I was quoted £40 by the company registrar for the replacement certificate but I would also have to take out an indemnity insurance with them (for about the same amount again) or a Lloyd's member in case someone else turned up with the original cert.
I wouldn't regard the cheap electronic "safes" as offering any more security than those lockable document boxes that hold 10-20 suspension files and which are much more useful for filing things in.
Owain