The date of issue of this interesting importer's catalogue would surely have been either late 1938 or very early 1939 by this time most British industry had been geared up to produce munitions for the imminent war which had been threatened for several years. Great Britain and France declared war on Germany September 3rd after the latter invaded Poland on 1st September 1939.
It would be quite easy to confirm that not many air rifles and pistols were made by W&S and certainly not for export in 1939. A US customer ordering a W&S air rifle/pistol would have been extremely disappointed aftersaving their pocket money.