Released in Britain last year, The Unfairground (Gigantic), by singer-songwriter Kevin Ayers is finally out in America on March 18th. It is actually a small delay, compared to the sixteen years that have passed since Ayers’ last set of new originals and his infrequent sightings since the Seventies, when he was the closest thing to a pop idol in English progressive rock. Blond and handsome, of impeccable pedigree (he was the founding bassist in Soft Machine) and beguiling baritone voice, Ayers examined love’s complex labors with a rake’s charm, majestic art-rock nerve and a mischievous tropical sway on early, masterful solo records such as Joy of a Toy (1969) and Whatevershebringswesing (1971). The Unfairground is a return to that devilish mettle, with Ayers joined by a small army of peers — like Roxy Music guitarist Phil Manzanera and singer Bridget St. John (Ayers’ duet partner in “Baby Come Home”) — and acolytes including Teenage Fanclub and the New York band Ladybug Transistor. “Shout, scream, ‘Give me back my dream, I need one to get through the day,’ ” Ayers commands in the string-drenched punch of “Brainstorm” — one of the ten affirmations of Ayers’ eccentric gifts on this very welcome comeback.