Courtesy of eBay (while buying something else for another member of the family) I spotted a little known rule-set (Recon) that would pair with a speculative buy (Advanced Recon) I had bought ages ago - once upon a time in the late part of the twentieth century [aka certainly pre-2000] - from a game shop that has long since closed (see below):
Thus the wargaming circle is complete - aka "I knew I had a reason to buy it". The US printed 'Advanced Recon' meets up with a copy of a UK licensed print copy of 'Recon' by the now defunct Platoon 20 figure manufacturers [once based in Northern Ireland]. Th extra bonus is that I have a collection of Platoon 20 Vietnam figures seeking a game (and I am pretty sure that the "Platoon 20 moulds" live on under the wing of another manufacturer). Again game-wise methinks this could be a 2020 affair but watch this space.