The Jos Arcus XS dynamo lamp (with capacitor standlight) is availabe from Decathlon (www.decathlon.co.uk) for just 12.99:
These lamps are bright (from a low speed (ie at low voltage, eg 4 rechargable AAs)), and have lots of room in the case.
(LED takes 25mA, so allowing 25mA to charge capacitor, that leaves 50mA xtra for front lamp or extra rear lamp).
The will/can be made to fit an L-type brompton: its lamp bracket slots may need heightened/lowered.
Jos Arcus XS dyno at Decathlon: only 12.99
Jos Arcus XS dyno at Decathlon: only 12.99
------------You may not use this post in Cycle or other magazine ------ 
Re: Jos Arcus XS dyno at Decathlon: only 12.99
Couldn't see the precise model there - are you saying it is an LED light or that it could be converted or something? There's a halogen lamp there - did you mean that one?
Re: Jos Arcus XS dyno at Decathlon: only 12.99
Its an LED rear lamp with standlight.
------------You may not use this post in Cycle or other magazine ------ 