From several of the public address systems that scattered the crowded thoroughfares, an almighty sound collage of Michael Jackson songs permeated the muggy air. The self-styled King of Pop may not, in his lifetime, have had any awareness of this king of rock festivals. But his death had an unlikely effect on it. For the first time in recent history, the heavens opened and, actually, no one seemed too bothered. One member of the group Friendly Fires was overheard uttering that, “even as we speak, ropey versions of Michael Jackson songs are being hastily rehearsed” — although perhaps mercifully, their thrillingly exuberant display at the Other Stage steered clear of mawkish tributes.

More than most, the American funk-rockers N.E.R.D. had reason to acknowledge his passing on stage. A few years ago, their producer-frontman, Pharrell Williams, was scheduled to produce a credible comeback album for Jackson, but the singer pulled out at the last minute, clearing the way for Williams to help to launch Justin Timberlake’s career. However, but for a cursory, “God bless Michael Jackson” in the middle of a protracted funk-rock workout called Sooner Or Later, the news went unmarked during the group’s mid-afternoon set.

Instead, he and his group came on half an hour late and attempted to blame the organisers when told that their arrival would mean having to shorten their set. Seeking to rally the ground behind him, Williams reminded them that they had paid “$200” to see a “full set”, seemingly oblivious to the fact that there were other bands dotted throughout the remaining 2½ days of the festival. Williams instructed the band to play on while petulantly flicking V-signs at the waiting stagehands.

While saying nothing about Jackson’s passing, Lily Allen accessorised in his name, thoughtfully donning a single white glove in his memory. Having been to countless Glastonburys throughout her life, Allen knows exactly what’s required. Save for the pink wig, her flared, blue trouser suit and Seventies eye make-up, had her more closely resembling a stunt double for Björn Again, who had played in terrible weather earlier that day. She breezily dispensed her best-known hits, Smile, LDN and The Fear, as well as a superbly dismissing interpretation of Britney Spears’s Womaniser and a touching “jazz” tribute to her watching father He Wasn’t There. Then she looked down, realised that her left breast was making a run for it and exclaimed, “My tit tape’s falling off — hahaha!”

Over on the Other Stage, Lady Gaga had no such qualms about modesty. Entering the stage in what appearing to be a sawn-off disco Dalek, she ended her set in a wholly see-thru outfit seemingly made of Perspex bubbles, nipples and buttocks gleefully visible. In one of the stand-out sets of Glastonbury 2009, the No 1 popstar managed to make a sunny field in Somerset feel like a scuzzy gay New York nightclub — combining cabaret, pop and disco in a manner which resulted in her playing a bluesy, ragtime version of Pokerface while almost wholly naked, standing on a piano stool, on one leg to awestruck applause.

Back over at the Pyramid Stage, it was the reformed Specials who turned in the first mass singalong. Ever since Glastonbury 2007, when Amy Winehouse and Allen featured songs by the group in their sets, the stage seemed to be set for the group to make their return here.

Fans who had not been born when A Message To You Rudy came out were word perfect. And as the setting Sun illuminated Worthy Farm, Michael Eavis beamed along with it. An unforgettable day for all the expected reasons and a few more besides.

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