Thanks for the info. I actually flew with it today, and it's the shift cable that gets squeezed against the fork. I could prevent that by cranking out the steerer fold 'stop' on it's threaded rod, but I'm a bit concerned that I'd be transferring the force from the fork / cable (which might get scratched but won't break) to the brazed-on threaded rod (which probably could).

In any case, I think getting some additional denser foam and following your example would be a good idea. I do wish Brompton would come up with their own hard-shell, although it'd probably be twice the price of the B&W...

Tangential, but since my last trip, I had also moved the shift lever in perhaps 1/4" (literally - no more and probably less) to fit Ergon grips, and in transit the shift cable housing was crushed / cracked against the slightly fatter central part of the S-bar because the cable run was moved inboard correspondingly. It's amazing how the smallest 'improvement' on the Brompton actually tends to mess something up. Obviously, the design has be refined incrementally over a couple of decades (and I should have cut the Ergons down).