As per the Bompton forum I like this.
As I said it will fit without any mod to the bracket and leave 2-3mm off the floor when folded. The supplied plastic bracket fits perfectly and you can even use the existing self tappers from the stock reflector fitting. No interference with the frame fold. Ising the supplied plastic fitting the Reflex can then be removed quickly if need be. I wanted more clearance so modified the stock brompton metal bracket so it sits further back. You have to mill the bracket to make the hole bigger (shown in the second pic) so that you can fit it on the other side of the long nut/bolt fitting. You then also have to cut the top fitting hole off the plastic bracket but it is not needed anyway. The Cateye Reflex comes with an optional auto mode which switches on in low light "and" when the bike moves. If the bike is stationary it goes off after 50 seconds. I am pleased with it so far. Only time will tell with its reliabilty.
I tried another cheaper light but although I could get it to fit it ended up interfering with the fold (it wasn't wasted as I fitted it to my wifes ladies bike). Here is a picture which shows the two lights and the reflector to give you an idea of size.
Regards
Jerry