Most of the Churches in England ( about 33,000 out of 44,000) have implemented a new technique to deal with thieves , who strip of lead and other valuables from the roof of those ancient buildings. This technique/system , named SmartWater , includes painting these valuable roof tops with a “nano paint” , which is visible only in Ultra Violet light. The nanopaint coating of each church is unique as they are coated with a blend of mixtures different from the other. This SmartWater technique proved to effective, when 3 thieves were caught stealing lead from the roof of St Leonard’s church in Colchester, Essex.
This SmartWater technique was developed by developed by Phil Cleary, a former police officer, and his brother Mike, a fellow of the Royal Society of Chemistry.
source : TimesOnline