Helsinki Vanity / Stavanger Desk  

Hi, I recently picked up a beautiful desk designed by Jan Kuypers for Imperial Furniture's Contemporary line back in 1952. It's in great shape but the original finish on it was ruined by a past owner. Here's a link to what one in perfect condition looks like:
http://www.designtraveller.com/50s_helsinki.html

Would anybody know the best way to replicate the color of that finish? The wood is solid birch, the same material used in the '50's Heywood Wakefield pieces but it's not the same finish. The only clue I have is that on the underside where it wouldn't show there are signs that a semi-opaque gray was laid on as the first coat, perhaps to neutralize the grain? Any help would be greatly appreciated.
http://www.dx.org/index.cfm?PAGEPATH=COLLECTION/Collection_Online/Furniture/999_7_3&ID=15540