The pigments are laid out on a cloth like a meal: ochre from a particular hillside, black from lamp soot, a white the painters still grind themselves. A child of perhaps nine is being shown how to load a brush without drowning it — the first lesson, and by all accounts the hardest.

This community has painted the same way for something close to four hundred years. The motifs are fixed by long custom, the order of the colours is fixed, even the songs sung during the work are fixed, so that the rhythm of the singing sets the rhythm of the hand.

It would be easy to romanticise this, and easy to condescend to it. The painters do neither. They are frank that the tradition nearly died — that a generation left for the cities and the brushes went dry for years — and equally frank that it survived because a few stubborn elders refused to let the children forget.

What is handed down is not only technique. It is a whole way of seeing: which shapes belong together, how much wall to leave empty, when a pattern is finished and when it is merely stopped. None of it is written. All of it lives in the hands of people who learned it from the hands of others.

I asked the oldest painter whether she worried the tradition would end with her. She laughed and pointed her brush at the nine-year-old, now frowning in concentration at her first clumsy garland. 'It will end,' she said, 'when there is no one left who wants the wall to be beautiful. And there is always someone.'