In many old brick buildings around London, youll find signs saying Ancient Lights marked beneath individual windows.

Here isa map of Ancient Lightssigns around London.

The phenomenon is not unique to London.

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Ancient Lights signs can be found in Dorset, in Kent and in many places across England.

‘Ancient Lights’ signs below windows in Clerkenwell, London.

The total deprivation of light is not necessary for the land owner to enforce the law.

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The levels of acceptable light, however, have not been objectively quantified.

Instead, the law uses vague expressions such as sufficient light according to the ordinary notions of mankind.

This has given rise to specialists and expert witnesses in this field, and the court relies on them.

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The law originated in England in 1663, but its current form is based on the Prescription Act 1832.

Photo credit:Matt Brown/Flickr

Ancient light signs under a window in Bournemouth, Dorset.

Photo credit:Alwyn Ladell/Flickr

Ancient light signs near a window in Bournemouth, Dorset.

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Photo credit:Alwyn Ladell/Flickr

Sources:Wikipedia/Freedictionary.com/Encyclopedia Britannica/Designing Buildings