IndiTD4's suggestion sounds the best option however, most high street locksmiths will hold L&F key blanks as a stock product, but there are plenty of variations.
(L&F manufacture tumbler locks for desks, vending machines and all sorts)
The locksmith won’t have a key cut to the code number but he should be able to identify the key and then contact Lowe and Fletcher’s factory in Wednesfield (0121 505 0400) who will have a record of the code number and be able to supply a cut key from their shelves.
I have been to their factory many times and they do keep records of the key profiles.
Alternatively, any locksmith worth his salt should be able to remove the cylinder from your rail and fashion a key to fit.