From the advent of the Bretton Woods monetary system in 1944, and indeed before, some countries required solid gold watch cases to be manufactured within their borders. France, Argentina, Brazil and the United Kingdom are amongst a group of countries that restricted the importation and free flow of gold and required gold cases to be manufactured in-country. It wasn't until 1971 that restrictions on the importation of gold cases were eased, allowing Swiss watch manufactures to export fully assembled solid gold pieces.
Records of Omega gold cases commissioned in Switzerland are comprehensive and accessible, however little information is available about ‘national production’ cases made to order locally for Omega agents in any of the countries mentioned above, and this has led to some confusion about the authenticity of locally cased Constellations and other Omega marques.
British Dennison Omegas are a case in point. Superbly crafted, these cases varied somewhat from the Swiss lines and have a different numbering system. Fortunately, collector Andrew Romaine has taken up the challenge to plug the information gap by researching and documenting the production of British Constellations and other lines. He has produced an essay (here) so as to share the fruits of his labours, for which we owe Andrew a vote of thanks!