As the mud dries in Glastonbury, revellers this side of the water are gathering their tents and fairy wings in anticipation of Oxegen this Friday. Comparatively, the two festivals offer different experiences – Glasto, being older and more established, is mellower; Oxegen is its boozier younger sibling – but the main event for many attendees at both events is the same: Blur are back and it's a return most triumphant.

There have been a number of hugely successful band reunions of late – Take That being the obvious example – but the Blur reformation last year caused waves of excitement amongst both critics and fans who thought they would never see the band on stage together again.

They are clearly no longer the young, cheeky Britpop heroes whose drinking bouts were legendary. They are four middle-aged men who have calmed down, sobered up and gone down different routes – including cheesemaking, law and opera writing – but who have put aside squabbles and side projects to emerge as electrifying as ever.

It's 21 years since singer Damon Albarn, guitarist Graham Coxon, bassist Alex James and drummer Dave Rowntree started their band, called, at first, Seymour. They met at Goldsmiths College in London where three of the members were studying. (Rowntree was a computer programmer with Colchester Borough Council.) Nearly three years later, having signed to Food Records and changed their name to Blur, they released their first album, Leisure. Inspired by the Madchester sound, it included the hit 'There's No Other Way', although Albarn has since described the record as "dreadful".

It was a 44-city tour of the US in 1991 which gave rise to Britpop, the musical movement that Blur are primarily associated it. The Stateside audiences only wanted grunge so when Blur returned home they set about writing songs that were quintessentially 'English'. Modern Life is Rubbish (1993) is identified as the first Britpop record and was followed by the albums Parklife (1994) and The Great Escape (1995). By now, the band was enjoying massive commercial success and was engaged in a very public slanging match with northern rivals Oasis. Both bands released a single on the same day in August 1995. 'Country House', which outsold 'Roll With It' by 274,000 copies to 216,000, became Blur's first number-one single.

But it was around this time that cracks first started to appear. Coxon, whose alcohol problems are well documented, hated the direction the band was taking musically. The partying was taking its toll on the rest of the band also. In his autobiography, Bit of a Blur, the ever-sociable James reckoned he had spent £1m on champagne and cocaine during his band years.

In 1997, the band took a low-fi turn with the Blur album. Its first single, 'Beetlebum', was a UK and Irish number one. 'Song 2', with its ridiculously catchy 'woo hoo' chorus, was a hit in the US and was used extensively in advertisements and TV shows. The next album, 1999's 13, was an even further step away from Britpop and included the songs 'Tender' and 'Coffee and TV'. Albarn's split with his partner of eight years, Elastica singer Justine Frischmann, influenced many of the bittersweet lyrics on the record.

Blur took a break and went off in various directions after 13. Albarn started 'virtual band' Gorrillaz with comic-book artist Jamie Hewlett; James had fun with actor Keith Allen and artist Damien Hirst as Fat Les, the band responsible for football anthem 'Vindaloo'; and Coxon started a solo career. When they started to record their next album, Think Tank, in Marrakesh, Coxon didn't pitch up for recording sessions and was kicked out of the band. The year of the album's release, 2003, they toured without him but didn't work together after that. Albarn wrote the score for an opera based on a Chinese story, Monkey: Journey to the West; James settled down in the country, became a farmer and made award-winning cheeses; and Rowntree enrolled at law school and is a former Labour candidate for the Cities of London and Westminster. Coxon, who quit drinking after a stint in the Priory in 2001, continued to put out solo albums influenced by the American indie scene.

So what brought about the reconciliation? One afternoon late last year Coxon turned up at Albarn's place and, according to the singer: "We went round the corner, had an eccles cake and what needed to be said was said. It took about 30 seconds for it all to be fine again."

With the success of the gigs, the obvious question is: will they release a new album? The band say they don't know yet and they'll see how they feel after the summer. If they do, it should prove to be interesting because traditionally Blur's music has evolved with each new release. "We're playing better than we ever did. We're experiencing such a positive revisit. The audiences are going crackers and are so happy. There's such a range of ages: there are people who weren't around 10 or 15 years ago, and there are fans who have waited a long time for this," Coxon says.

For Albarn it's all about picking up where himself and Coxon left off, professionally and personally. "The main thing," he says, "is that it's really nice to know that I can call Graham and he'll pick up the phone, and it's all cool, you know?" Woo hoo.

Curriculum Vitae

Names: Damon Albarn, (singer, pianist and principal songwriter), born 1968, Whitechapel, London; partner is artist Suzie Winstanley; one daughter, Missy (9)

Graham Coxon (guitarist), born 1969, West Germany; one daughter, Pepper (9).

Alex James (bassist), born 1968, Bournemouth; married to Clare Neate; has three sons, Geronimo (5), Artemis and Galileo (4), and a daughter, Sable (11 months)

Dave Rowntree (drummer), born 1964, Colchester; divorced from wife Paula

Group career: Formed 1988. Albums: Leisure (1991), Modern Life Is Rubbish (1993), Parklife (1994), The Great Escape (1995), Blur (1997), 13 (1999), Think Tank (2003)

In the news: Reformed and headlining at Oxegen