The wheels with Dunlop special lightweight rims are almost certainly original to the bike. The other components I'm not so sure. The diameter of the seatpost is a good indicator of frame quality- or quality of the tubes anyway. Some of these old British lightweights have butted Reynolds tubes despite the plain dropouts and claw mounted rear derailleurs. My hunch is that is case with your Armstrong. Value is pretty modest - $150 maybe $200 US where I live.