I put Ergon GC3 combo Bar-end/grips, shorter grip-shift pair, find the brakes can be reached,
using the tip of the lever, but the little ball on the end of the lever is not a great grip surface.
these would perhaps help, but bar may not fold down, as well .
http://store.velo-orange.com/index.p...s/br-0024.html
Edit: just dug out some 2 finger MTB Cantilever levers [Dia Compe pc700 fwiw]
and took the original brommy ones off,
removed Bromptons fancy teflon-coated cables, as they, once cut
as they were in the factory build, refused to go back in the housing without fraying .
and there were already bare spots of coating , in the cable, I pre soldered the next cable,
so I could cut it without fraying.. pull and re grease easily..
little curved section in the lever helped the middle/ring finger , grip the lever,
with out sliding further.
straight lever , hand slid too close to the pivot, so leverage under-hand was reduced.
the Ergon GC3 Grip shift shorter version, plugs right in, no cutting..
Older Mk 2 bikes had M bar with a center sleeve, 15/16 tube,
a no go for 7/8 bar controls .. newer MK 4 replacements, fine.