IT WAS music promoter Geoff Ellis who came up with the name, a simple play on words that even a team of beard-stroking creatives couldn't better.

In an early meeting, he even sketched out a grassy-T logo, an emblem that would go on to become synonymous with Scotland's biggest music festival.

And it was Geoff who booked the few dozen bands for the very first T in the Park, at Strathclyde Park, exactly 20 summers ago.

However, even the chief executive of DF Concerts himself admits to being a little bewildered that the event that he and his predecessor Stuart Clumpas devised would go on to reach its current anniversary.

"If you said to me back then we'd be celebrating 20 years, it was just never in our thoughts," admits Manchester-born Geoff, 47, who came to Scotland in 1992 to manage King Tut's Wah Wah Hut on Glasgow's St Vincent Street.

"We never thought we'd do a festival for three years or for five years.

"But we didn't put an end date on it. I guess if it's not broken, don't try and fix it."

The festival director is having a pint with George Kyle, the head of sponsorship for Tennent's Lager, in Glasgow's Wellpark Brewery's new visitor centre.

It's only fitting that they're sitting on stools fashioned from old amplifiers at a table covered in memorabilia from the last two decades of T in the Park.

The partnership between DF Concerts and Tennent's predates the first T in the Park by more than six years.

The companies had worked together closely on the Tennent's Live series that staged more than 2000 gigs since 1988, ranging from pub venues in Skye and Orkney to Edinburgh Castle and the SECC.

DF Concerts founder Stuart Clumpas approached Tennent's sponsorship manager Scott Meneer and its brand director Mark Hunter about putting on a multi-stage outdoor event in Scotland.

DF twinned with the Féile festival in Ireland to share their acts over a weekend, and the first festival at Strathclyde Park was born.

In the first year, 17,000 music fans watched the likes of Cypress Hill, Rage Against The Machine, Bjork, Crowded House – and a couple of complete unknowns called Oasis and Blur.

Kylie Minogue and Keanu Reeves were among the big names in its first three outings in Lanarkshire, but it wasn't until T moved to Kinross-shire in 1997 that it really found its feet.

It now attracts up to 250,000 people over three days, drawing fans from across Britain and Europe.

"The event has constantly evolved," says Geoff.

"You've got to keep it fresh; keep it at the cutting-edge of music.

"We have people in their forties and fifties coming to T in the Park, but the vast majority are in the 18-25 age group."

T in the Park is now the longest-running musical sponsorship agreement in Britain, out-lasting even the Brit Awards' 15-year association with Mastercard.

George Kyle, who joined Tennent's 22 years ago, worked as an accountant in the brewer's marketing department when the first festival took place.

Since becoming head of sponsorship, he now works closely with DF Concerts to deliver everything from the bars to the branded plastic pint cups used at the festival.

"I've sat with Geoff over the years and we talk now about what is the partnership and what's the model – we created the model," says George, 49, whose two sons, aged 21 and 18, attend the festival.

"Brands didn't do music back then, never mind do festivals.

"You look across the world now and it's so familiar – so many brands either create music events or back music events or get involved in music events, but that was never what T was.

"T in the Park was a joint ambition and a joint project, a joint love affair."

On visiting the site at Balado last week, Geoff says that he went for a whirl on the fairground's big wheel for the first time, giving him a vantage point over the entire site that he had never seen before.

After more than 12 months of planning, he knows that the reality of the 20th year will only hit home when the campsite begins to fill later today ... when music fans turn vocal.

What you hear is the T in the Park roar," smiles the dad-of-two, who earned a lifetime achievement award at the UK Festival Awards in 2010.

"It starts to happen probably about an hour or so after most of the people have pitched their tents.

"You just hear this noise building up and you get this cheer and it goes around the campsite.

"It's like a vocal version of a Mexican wave, a primal scream or something. But it's deafening.

"That always makes me think: 'Right, we're on. The festival has started.'"

This year's programme features more than 200 artists, including Mumford & Sons, Rihanna, The Killers, Calvin Harris, Snoop Dogg, Rita Ora, The View and Emeli Sandé.

After tickets for the 2010 festival sold out within 90 minutes, organisers have put this year's slightly more sluggish uptake down to the economic downturn.

To mark the 20th year, there will be 'T20th' logo pint cups, twice the number of fireworks as last year, and also a fire-breathing dance attraction added to the Sunset Strip entertainment zone.

"From our point of view, I'm conscious that it's our 20th year, but for most of the audience, it's their third year, fourth year, fifth year or even their first year," says Geoff.

"It's about putting the resources into making it a great event, rather than a specific 20th anniversary."

Every year, the explosive finale is what makes the hairs on the back of George Kyle's neck stand up.

"There's so much invested in the event by so many talented people," says George.

"Some have worked together for 20-odd years, some just come together for the weekend.

And at the end, as a band finishes on the main stage, and you have the piper and the fireworks, I defy anybody not to feel the emotion."

DF Concerts, which organises everything from Glasgow on Ice to the Papal visit of 2010, was recently granted a two-year extension to its public entertainment licence by Perth and Kinross Council.

The timeline of Tennent's history on the wall opposite the two men stops at the present day.

Should a space be made to extend the T in the Park timescale by another two decades, say to 2032?

"I can see it certainly outlasting the two of us," admits Geoff.

"It's no longer a music festival that we've chosen to put on – it's like a kid who has grown up and left home.

"The festival is a rite of passage.

"I don't see there not being T in the Park. It will outlive us."

l T in the Park runs from tomorrow until Sunday. Tickets from or 08444 999 990.