We are all bothered from time to time by unwanted light from things like security lights or the permanent orange glow in our towns. The following information has been taken from the DEFRA guidance 'Statutory nuisance from insects and artificial light':
Artificial light nuisance may be, but is not necessarily, the same as light pollution. Artificial light nuisance is a source of light that in the opinion of a trained public health professional, who makes an assessment on a case by case basis, interferes with someone's use of their property, and / or is or might be prejudicial to someone's health. Light pollution could be defined as any form of artificial light which shines outside the area it needs to illuminate, including light that is directed above the horizontal into the night sky creating sky glow (which impedes our views of the stars), or which creates a danger by glare. Although light pollution might affect the aesthetic beauty of the night sky and interfere with astronomy, it is not necessarily also a statutory nuisance.
For more information see the following pages.