About 4, 000 boat owners are to be given the liquid - which is invisible to the naked eye - to paint their property.

BBC: Boat owners in Hampshire given anti-theft paint

Mr Plotnik and his colleagues placed a white cross above the elephants' right eyes and an invisible cross over the left eye, so that neither smell nor a memory of paint being applied should tell the elephants where the conspicuous marking was.

ECONOMIST: Self-recognition

So much is red in the surroundings, that the eye takes unexpected pleasure in anything that is not red - the gold paint on the inside of the church, the deep blue of Mary's cloak, as she holds the crucified body of Jesus in her arms.

BBC: Villagers despair in Hungary's red wasteland

Since then, conservators have uncovered eye-catching drawings of horses, women and soldiers, long hidden beneath layers of paint and wallpaper.

BBC: The writing��s on the war