From Bramford Mike....

Hi Martin
Nice bike! I've just finished a 1958 Moth for my brother in law. We bought the bike earlier this year from the widow of the owner who'd originally bought the bike in 1960/61 . He'd had the bike renovated at a local dealer a few years before his death which involved a new paint job,wheels(700c - yuk!), chainset(SR) ,new front mech(shimano Ultegra) and new Brookes B17. The bike came with its original wheels but unfortunately not the other missing parts. The frame number is in the "A70000M" series which dates it as late fifties. I have been told recently by another "super" Moth owner that the "A60000M" series numbers relate to early to mid fifties frame numbers.
From what I can deduce from the widow's description of the missing parts plus what arrived on the bike the spec is/was as follows:-

Frame and Forks - 531 d/b tubing(27.2 seat tube) with Nervex "pro" lugs - and "Cyclo" ends - forks,dropouts and gear hanger - braze ons - Single "Cyclo" gear lever boss(takes "Cyclo/Simplex" levers) on right of downtube and offset to left on downtube 2 pump pegs(this presumably stops pump interfering with gear selection). Lamp mounting boss on RH fork leg. - seat stays are the "pencil style" which "wrap" over the seat tube lug and finish neatly butted up to each other. Chainset - Campag "Gran Sport"
Pedals - Chater Lea
Wheels - Fiamme "tubulers" with Campag "Record" composite hubs – rear double sided(composite - chrome steel barrel/alloy ends)
Gears - Cyclo/Simplex - rear coupled with Campag "Gran Sport" bar end front changer
Brakes - Mafac "dural" center-pull(pre "Racers") with Mafac levers(1/2 rubber hoods)
Bars - "GB" - not sure which model
Stem - "GB" - this was cracked at the clamp bolt area so has been replaced with Cinnelli.
Seat - Brookes B?? - 15 or 17

The spec on your bike therefore does not seem to be too far out. Armstrongs made Moths throughout the 30's - 60's. They were a company more involved with "utility" bikes(similar to "Hercules") but the Moths were renowned for being top quality lightweights. The company was finally absorbed into the "Phillips" empire which in turn was bought out by Raleigh