Blur - It looks like we might have made it to the end

Blur are marking 21 years, and possibly their final days, by re-releasing almost everything they have ever recorded. Andy Gill discovers a host of unheard gems

Blur in 2012 and 1991

If, as Damon Albarn has suggested, Blur's Olympic Closing Ceremony gig on August 12 is to be the band's final performance, then the Blur 21: The Box package released this week makes a pretty hefty marker for their career: less a tombstone than a musical mausoleum, its shelves stacked with artful brilliance, euphoric pop, and questing exploration.

It's a reminder of just how far Blur travelled in such a brief period of time, especially given they have only released one album this century. But the 1990s were indisputably theirs, a career captured on six albums that express the decade's hopes, ambitions and uncertainties with uncanny prescience, their shifts in approach always a step ahead of social changes. Months before New Labour's victory in 1997, they released Blur, an album fraught with misgivings and marked by a musical volte face against the brightly-coloured excesses of the Britpop era they had invented. Shortly after, Britpop was just a gaudy stain in the gutter, and shortly after that, the first cracks of disillusion appeared in New Labour's shiny edifice.

Blur offered a barometer of the direction things were moving. Indeed, despite widespread predictions that Blur was career suicide, it actually became their breakthrough album in America. Ironically, the group was by then starting to atomise into its constituent parts: guitarist Graham Coxon was chafing at the restrictions imposed by pop stardom; drummer Dave Rowntree was becoming interested in politics; bassist Alex James was en route to becoming Cheesemaker General; and Damon Albarn was beginning to flex the artistic muscles that would make him one of the most accomplished musical explorers of the next decade.

Named for the 21 years since Blur's debut album Leisure, Blur 21: The Box contains 21 CDs, with each of their seven albums accompanied by a disc of bonus material. But it's the four additional CDs of "Rarities" that will most pique fans' interest, a hoard of unreleased material that itself offers a sort of musical commentary on the band's progress from tyro indie boys to national darlings to troubled troubadours.

The earliest material is culled from rehearsals and demos when the group were called Seymour, beginning with "Dizzy", a track which starts out scratchy, lo-fi and insular, but gives way to bouts of energetic slickness: it's indicative of the two-way tugs between pop and rock, mainstream and fringes, that would contribute to Blur's creative momentum throughout its career.

When producer Stephen Street becomes involved for the Leisure sessions, things become clearer, though no less diverse: "I Know" is a raggedy funk groove despoiled with errant noise, Graham Coxon infuses "Always" with sparkling guitar of a darkling cast, and "High Cool" is a Madchester baggy-beat with a mockney makeover. Throughout this period, one gets the impression of Blur as a sponge, soaking up influences – The Smiths, Stone Roses, REM, Ride, Pavement. It's as if they're still carving their own sound from raw materials – a task they'd never quite complete, their "own sound" altering all the time, moving on before they could pin it down.

A salutary experience of their early career came when they arrived for their first tour of America on the day that Nirvana's Nevermind was released, and found themselves surplus to requirements, as the country turned plaid overnight. Stung by the indifference, they resolved to emphasise their Englishness, a shift that furnished the seed-corn of Britpop in the Modern Life Is Rubbish album. Outtakes such as "Death Of A Party" and "Pap Pop" are in the self-deprecating, ironic vein of UK melancholia that stretches from The Kinks to Bowie and The Smiths. But it's the tracks produced by XTC's Andy Partridge that are the most exciting, particularly a take of "Coping" as edgy and thrilling as a 1960s psych-rocker, and a version of "Sunday Sunday" with a Beatlesque tone, in the parochial-rococo manner of Magical Mystery Tour.

In a way, Blur became less interesting the more tightly characterised they became, with the Parklife album. The outtakes and rarities from that era, and through The Great Escape, are less intriguing, more bounded by their image. It's fun to hear "Parklife" itself sung by Damon, but sadly there's no alternative version of "Girls And Boys", which furnished their commercial breakthrough. At the height of the band's success, the rarities dissolve away. The shortfall is most frustratingly felt on the sessions for Blur, which offers little more than a demo of "Beetlebum".

The outtakes from 13 reflect that album's improvisational methods, with the group's lengthy jams edited into workable shape by William Orbit: the dark, dubby "Battle" jam is featured in its entirety, along with an eight-minute "Caramel" on which Blur partly revert to their shoegazing days. A long take of "Music Is My Radar", called "Squeezebox", and two numbered takes from sessions with Bill Laswell bridge the years to the band's swansong Think Tank, on which the absence of Graham Coxon is decisive. There's a touching break-up ballad, "Sir Elton John's Cock", and a funky electropop "Don't Bomb When You're The Bomb", but the disruption clearly threw Blur out of their natural orbit – an orbit which, if Albarn's hints prove reliable, will never be regained beyond this August.