A week after one famous rock grump departs these shores and another, homegrown one appears over the horizon, you do have to wonder – at what point does a music legend stop being a thriving, evolving artist and simply become a museum piece, churning out the same old songs for a diminishing audience?

While he may not have undertaken such drastic career re-construction work as Dylan, Van Morrison has without doubt dabbled over the years. After the folk, skiffle and rock’n’roll, his current inspiration is the blues and r’n’b that informed his early band days.

All of which means his Marlay Park performance is light on the soul-searching introspection of his early work (aside from the two, glorious moments when he dons an acoustic guitar and lets that particular side to his muse break free) and heavy on the bass, drums, guitar and – especially – brass of his latest band. At first it’s all a little disconcerting – far too leaden and uninspiring – but as the beautiful summer’s evening draws in it would be churlish to deny that, in the right setting, he can still work wonders. There’s an added bounce to ‘Jackie Wilson Said’ and ‘Precious Time’ (almost approaching a ska number tonight) while later work such as the exquisite ‘Days Like These’ sits well next to those poignant ’70s classics. ‘Brown Eyed Girl’ may have emerged unscathed from years at the hands of countless covers bands but is curiously lacklustre here – far better is the spiky version of ‘Gloria’ that closes proceedings.

Morrison himself is typically contrary – barely acknowledging the audience, lyrically unintelligible and appearing to produce the set list from the top of his head – but who’d have him any other way? On this showing, no one.