Proposed Union Jack (1604) - Design 1 of 6.
Based on File:Union jack proposed.jpg, uploaded 11 January 2012, which explains "Proposed designs for the Union of Crowns circa 1604.Manuscript in the National Library of Scotland. Immediate source: BBC News.
The hand-written note is signed Nottingham, recommending the lower-middle design as "like man and wife". 

Source: http://news.bbc.co.uk/2/hi/uk_news/magazine/4895076.stm
Archive: https://web.archive.org/web/20201130134900/http://news.bbc.co.uk/2/hi/uk_news/magazine/4895076.stm
Own work
RCraig09