Set in the immaculately landscaped grounds of a 17th-century stately home in Charlbury, Oxfordshire, the Cornbury Festival is a rather more upmarket pop gathering than the norm. Plenty of space, delicious food, agreeable lavatories. No wonder people were calling it Poshstock.

“It’s certainly a bit different from the V Festival last year,” said Robert Plant, approvingly, as he introduced Let The Four Winds Blow. Unfortunately, the song produced its own instant karma, and no sooner had his group the Strange Sensation struck up the twanging voodoo-blues riff than a gust of cold wind brought the first drops of rain to fall on an otherwise balmy summer day.

His rain-making talents aside, Plant was the ideal act to headline this event. A performer who combines a distinguished history with an inquiring musical mind, he took a canny path between revisiting old favourites and forging ahead into fresh territory. The songs from his latest album, Mighty Rearranger, had a rootsy, ethnic feel to them. Tin Pan Alley, with its Indian tonalities and a guitar part that sounded like a sitar, addressed the besetting problems of an ageing rock god: “My peers may flirt with cabaret/ Some fake the rebel yell/ Me — I’m moving up to higher ground/ I must escape this hell.”

But the very next selection was a version of the old Led Zeppelin song Black Dog, and it quickly became apparent that, far from denying his legacy, Plant had reached an accommodation with his past that was to prove acceptable to all parties. For this was no slavish re-creation of the heavy-rock anthem, more a reinvention of a classic text. De-metallicised, and given an almost English folk-song spin, the number took on a new life while staying true to the rambunctious spirit of the original.

Plant shook his blond curls and wailed with coquettish vigour. An exquisite version of Going to California — all twinkling mandolins and Far Eastern cadences — gave way to an ethereal 29 Palms that was stripped of its backbeat and turned into a ghostly reverie. Friends and Gallows Pole, both from Led Zeppelin III, were a tour de force of hand drums and acoustic guitars, while the rhythmic ingenuity and sheer energy of Four Sticks was a tonic for the soul.

They ended with the boldest stroke of all — a version of Whole Lotta Love that reprised the familiar, air-punching riff, and then went careening off into the sort of gypsy-punk shenanigans that you might expect to encounter at a Gogol Bordello gig. A mighty rearrangement indeed.