In a garden studio in north London, Steve Altman holds a monthly shamanic drumming circle. Participants stand with arms outstretched as Mr Altman traces their shape in the air with burning copal, a Mexican incense, in a purifying ritual known as “smudging”.

Ground snake skin, feathers, candles and bowls of water, each representing the four elements of Inca cosmology, sit in the centre of the room. The ceremony culminates in a “soul journey”, in which rhythmic drumming is believed to facilitate an ascent to the spirit realm. One woman describes climbing vines to the heavens. From Colindale.