Current issue of Antiquarian Horology (Volume 38, Issue 1, March 2017) has an informative article on Smiths, including a major focus military timepieces.
The National 15. The decline of British watchmaking and the role of Smiths in a hoped for recovery
by David Read (pages 74-89)
Summary: By 1870, the development of factory based manufacturing in the USA had changed the nature of the horological industry. The Swiss responded and modernised, but the trade in the UK resisted change, and declined dramatically as a result. In consequence the United Kingdom entered World War Two without a horological industry that could provide the high grade watches that were an essential strategic resource. A significant proportion of what was left of British clock and watchmaking, including H. Williamson Ltd, had been acquired by Smiths and the government was keen to support a national revival of the high quality segment of the industry that would match the specifications laid down by the Armed Forces and would, in due course, form the basis for successful domestic sales. How this was achieved forms the subject matter for this article.