In many old brick buildings around London, you’ll find signs saying ‘Ancient Lights‘ marked beneath individual windows. The best examples are the back windows of the houses on Albemarle Way, which are visible from Priory Church of the Order of Saint John just off the Clerkenwell Road. You can also find these odd signs near Chinatown and Covent Garden, particularly in back alleyways, and one in Newman Passage and another one in a pub just near Goodge Street tube station. Here is a map of ‘Ancient Lights’ signs around London.

The phenomenon is not unique to London. ‘Ancient Lights‘ signs can be found in Dorset, in Kent and in many places across England. What are they?

'Ancient Lights' signs below windows in Clerkenwell, London. Photo credit: Mike Newman/Wikimedia

‘Ancient Lights’ or the ‘Right to light’ is an English property law that gives house owners the right to receive natural light from and through a window if that particular window has been receiving light uninterrupted for 20 years. Once a person gains the right to ancient lights, the owner of the adjoining land cannot obscure them, such as by erecting a building, raising a wall or planting trees. In the past, neighbors with right to light have sued neighbors on grounds of ‘nuisance’ for obstruction of light, and have won in courts of law.

The total deprivation of light is not necessary for the land owner to enforce the law. He can challenge the neighbor if he feels he “cannot enjoy the light in so free and ample a manner as he did before,” as explained by Collins Dictionary of Law. 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.

One so-called expert, Mr. Percy Waldram, suggested that ordinary people require one foot-candle of luminance (approximately ten lux) for reading and other work involving visual discrimination. Waldram's methods has been in use since the 1920s, but recently they have been subjected to much criticism.

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. Photo credit: Alwyn Ladell/Flickr

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