Best Headlight suggestion for your Brompton
CatEye HL-EL530 Headlight

     Cat Eye's HL-EL530 produces an amazing 1,500 candlepower from a single LED. The OptiCube lens technology puts the light right where you need it. This innovative light also features side visibility for safety and is water resistant. And, it runs up to 90 hours on the 4 included AA batteries.