Thanks all. I had red somewhere that it's not just the lever touching something when folded that is the problem when it comes to the levers, it's that when you move them it affects the cable run somehow. Anyhoo, I can just try it.
I have, in the past, used a Mk 1 bit of string cut to the right length, as a reference for this sort of thing.
Noted.
I think after a bit of fettling, brake lever adjustment, attaching of lights, and additional folding practice, we may be almost ready to move beyond merely admiring our Brompton, resplendent and shiny in our living room, towards actually riding it.