"IT'S only an A chord," John Martyn protested, somewhat embarrassed as yet another wave of encouraging whistles and cheers greeted even his pre-song noodlings on the guitar.
But one could understand the diehard fans being even more vocal than usual. After 37 years as a sometimes-overlooked genius of British singer-songwriterdom, Martyn has just produced one of his best albums in years, On The Cobbles - all while in the throes of an illness which necessitated the amputation of his right leg.
So, resembling a wounded grizzly bear, the burly 55-year-old singer walked ponderously on stage with the help of his new prosthetic leg and a large shepherd's crook, sat down and launched into that ethereal combination of folk, jazz, blues and rock which has made him so difficult to pigeonhole and so hard to market.
His most striking new song is My Creator, a pining hymn of spiritual exploration, which it is tempting to see as Martyn's own epitaph.
But when that sad day comes, perhaps the only one of his songs which the general public will certainly recognise is May You Never, delivered as an exquisite solo spot which transcended even the truly awful tone of Martyn's amplified acoustic guitar.
He treated us to a few oldies, such as Solid Air, Big Muff and The Man In The Station, but more fascinating is the complex later material, which often modulates between just two chords, depending on pure dynamics and emotion, plus the fine contributions of musicians like bassist John Giblin.
In this dreamy context Martyn's voice - given to some odd cackling and coughing between songs as it veered between cockney and Scottish accents - became an instrument all of its own.
The consonants were smoothed away, and it soared up to keening highs or down to burred, rasping lows, just like a human saxophone.
The troubadour slowly took his leave of us and the theatre lights went up, but the crowd were having none of it. Their justified applause carried on until Martyn returned for an encore.