Update to Post 183 & for 400:
1. SRF back together, locking cone washer added
2. Gearing now 44/15 & much improved (new chainset, bb, chain & sprocket)
3. There were some thoughts that Bromptons (at one point) left the factory with none too generous bearing care - redone, as was the headset & folding pedal
4. Frameset rust treated (messy - will know better next time!), handlebar stem freed & reset
5. Wheels trued
All ok.
Such a fabulous practical design and London success story: still a wonderful bicycle.