In his 2015 memoir Unfaithful Music and Disappearing Ink, Elvis Costello recalled an early gig at the British Legion Hall “on the posh side of Birkenhead Park” in Birkenhead, Merseyside.  “I can’t say my set was a triumph,” he wrote.  “I went off to a round of feeble applause from a handful of pensioners supping mild beer and a smattering of teenagers in army petticoats drinking cider.  However, once I found a singing partner in Allan Mayes, my performances became a little more controlled and his superior musicianship and more melodious voice…