FOR less than £300 per 200 metres, an early-warning infra-red alarm beam can be set up which phones five separate numbers immediately the beam is broken by someone crossing through it.
For example: York CCTV, police, fire, ambulance or river rescue boat could be rung while someone was contemplating doing something silly but before they even got wet.
Deployment could be timed between 11.30pm and 5am with warning signs and fines to deter pranksters.
I found this information by Googling infra-red security beams.
Kevin J. Ward, Lindsey Avenue, York.