I haven't commented up till now because my Brompton has neither standard cables nor standard chainset (my chainrings are significantly smaller, which probably helps to avoid rubbing issues), but since I had to work it all out from scratch, I ended up with an arrangement where the rear brake, gear cable and rear light cable were all cable-tied together as a single bundle from cable-gatherer to bottom bracket (using IIRC three cable-ties). It works.