Thank you all.
With all your assistance, progress seems to be being made.
It is becoming clear that Downey did draw up designs for companies other than Vitrea. There is an increasing body of evidence that Downey also designed in his own right, though some confusion as to the status of Vitrea and its links to Glassexport at that time.
However, I have managed to find the current contact for Vitrea, and am hoping their company records may reveal something.
Clearly Downey designed work that was produced at three of the factories, and clear overlap of production numbers, possibly indicating the popularity of certain items, needing to be made simultaneously by two production units.
On Downey's time-line, we now know was working in 1963, definitely in the 1950s, and one Hermanova hut pattern number suggests 1947-48. Allowing for education and training, maybe military service, E Downey could possibly have been born between 1910 and 1920.
I have a couple of calls to make this evening, so we may have something concrete later.
My thanks again to all of you,