Get Some F**king Lights

Anyone recommend a decent clip on rear light, preferably with flashing mode?

I use the Brompton saddlebag which is open at the top, so there isn't a loop for attaching a light - so it needs a clip (reasonably strong one, so it doesn't ping off over a bumpy surface).

I have a Skully rear light but nowhere to really attach it, unless I offset it slightly on one of the saddle loops.

IME the RSP Astrum is good value and very bright. There is a pic here of the mounting system and the clip so you can see if it works with your bag.
http://www.highonbikes.com/rsp-astrum-2-x-1-2-watt-led-rear-bike-light-laa918.html