JANE BIRKIN DIDN’T much like the terribly sophisticated Serge Gainsbourg, 18 years older than she and already a famous singer, when she met him after being cast in the French film Slogan in 1968—she found him arrogant and snobbish. Or perhaps more to the point, she was convinced that he didn’t think much of her, a 21-year-old English actress who’d blown up after appearing, full frontal, in Antonioni’s Blow-Up, which was quite scandalous at the time. But she fell for him when they went out dancing, she’s always said. He kept stepping on her toes.
“To find out that, in fact, he was extraordinarily timid and, yes, it was all just pretense,” recalls Birkin on a bright winter afternoon in the empty nightclub atop the Standard High Line, opened to…