EVER SINCE he emerged from an unhappy south London childhood in 1978, fronting Japan, glam ugly ducklings in the post-punk era, the boy christened David Blatt has shown remarkable powers of recreation. In recent years, following a path set by his Indian guru, he moved around America before settling in New England with his wife and children. This rare visit to London showed that his musical creativity - assisted by collaborations with Robert Fripp, Ryuichi Sakamoto and Holger Czukay - is still ripe and evolving. And he's received by a devoted following, nurtured over 20 years and eager to bathe in his sumptuous and singular blend of avant- garde jazz, exotic Eastern influences …