So I’ve some lights that I’ve been using on the bars but would like to put on my lid. Specifically, a Mavic Notch.

Now the lights are the standard curved piece of plastic and an O ring affair, which doesn’t lend itself to mounting on a Notch:

Notice that there’s no convenient centre line of holes to use… The light mounts are lacking in adjustment too (it’s almost like 30 quid lights can be shoddy!) so I can’t really put them on a side slot and tilt them.

Beyond buying some better lights, does anyone have any cunning ideas?

Not sure what light you have, but it’s not uncommon for there to be a phillips machine screw underneath the curved rubber pad, enabling you to remove the curved mounting part.
Makes it easier to screw it to something that is designed for helmet mounting, either from USE, Hope or GoPro style from Fleabay…

Have a read through this lot, it’ll give you a few ideas…

http://forums.mtbr.com/lights-diy-do-yourself/magicshine-gopro-replacment-mount-842362.html