The Armstrong looks pretty glorious, congratulations. A 50s machine clothed in parts it received early in it's life is a happy find.
It seems to have horizontal dropouts for derailleur gears but no cable guides or other braisings for them. The mech might be a Cyclo Benelux Mk7. I think it is.http://www.classiclightweights.co.uk/cyclobenelux.htmlhttp://www.disraeligears.co.uk
Getting them working is a challenge but achievable with perseverance.
The GB Coureur brakes are desirable. The steel stem is one I don't recognise, which might be a good thing. Are those handlebars original? The Maes type bend looks quite useful. The saddle looks in good nick!
I think flip-flop hubs were popular in the day. My 1951 Harden hub is the same.
Getting everything working and making it your size whilst keeping the original character is the trick in my opinion, but other opinions are available.
"When I see an adult on a bicycle, I do not despair for the future of the human race." - H.G. Wells