1916 REGISTERED STATIONERY BERNARD CATFORD GOLD or WATCH GB to SWITZERLAND 24oz

KG5th pre-paid 3d postal stationery Registered Letter from Catford London S.E, W. Bernard to Fabrique Aureole, Chaux de Fonds Switzerland; uprated with 5d + 2 1/2d stamps; Catford CDS + Registered oval cancels.  WW1 period.  2d Registration + 2d for first 2 ounces + 5 1/2d at 1/2d per 2 ounces = 24 ounces.  Seems too heavy for a watch, the shape suggests a gold bar!