Energizer Headlight LEDx3
I finally decided to buy one to check it out - having thought twice as recommended by Steve.
The construction is fairly cheap and cheerful. I had no problem opening the torch to install the batteries (a large screwdriver is perfect for this although a 1p works nearly as well). Closing the torch was simple a matter of locating a tab in the correct place and snapping it shut. The on-off switch is a rather flimsy slide-switch and I can see that it could come on accidentally in a rucksack. However, this potential problem is easily solved by cutting a thin strip from the plastic packaging the torch is sold in and sliding it between the battery contacts before closing the torch. To use the torch, it is them simply a matter of gently pulling the plastic strip out (no need to open the torch) which restores the battery connection.
The light from the torch looks very good as does the red LED. If the weather is okay tonight I may try a night activation to test the torch.
Incidentally, it gets good reviews on various fishing websites. There they note that while the construction of the torch is clearly not waterproof, it works fine in the wet. I am sure that the Petzl equivalent would be much more substantial - but also more expensive.