Given all that Kevin Coyne went on to achieve in his own right, his apprenticeship in Siren remains just that, a learning curve that brought out only occasional flashes of his later acerbity, while the band blues-boogied along behind him. But what flashes they are, from the effortless churn of "Relaxing With Bonnie Lou," with its invocation of Coyne's later "Eastbourne Ladies" shamelessly doing the can-can behind it, to the Stax-y soul of the title track, an R&B shouter in everything but the R&B…