I'm looking for a cheapish (under £100) B&W CCTV camera (with composite
output) to monitor a field on moonlit nights. I'm not looking for
image-intensifier brightness, just the ability to distinguish vague
shapes, and to see anyone sneaking around with a torch.

Ten years ago, it was possible to buy a CCD-based Philips Toucam Pro
webcam that could do this, but all cheap "night vision" composite-output
cameras now seem to rely on IR LEDs, which won't work with a large field.

I've got a B&W CCTV bullet camera which claims a sensitivity of
0.005lux, but in reality it can't see much.

Any recommendations?