In reply to TheDrunkenBakers:
Alternatively you can get a very small red light to clip to the back of your existing headtorch band, e.g. Alpkit blip, which is cheap and lasts for ages before you need to change the CR2032 (or something of that ilk) battery.
Edit: LED Lenser H7R.2 has integral rear red light.
Post edited at 20:01