A sea of tents in Knebworth Park during the 2010 Sonisphere Festival weekend

SONISPHERE Festival organisers are already planning next year’s hard rock and metal extravaganza at Knebworth Park.

Following the freak, storm-lashed final date in the travelling festival’s European tour in Finland last weekend, a statement on the Sonisphere website says: “And so to the next round of Sonispheres.

“Team Sonisphere have started planning already and we’re very excited about what’s in store. Stay tuned.”

Alice Cooper, Rammstein and Iron Maiden headlined at Knebworth this year and Sonisphere officials put up the sold-out signs over the weekend for the first time in the UK.

More than 50,000 ticket holders turned up at the gothic stately home on the Saturday for German industrial metallers Rammstein’s British festival debut, including Sonisphere’s one millionth customer, with 55,000 there for heavy metal legends Iron Maiden the following night.

An estimated 35,000 were camped in the Hertfordshire country estate for the new Friday evening of music – something that will be repeated next summer provided a suitable headliner is secured.

However, series creator Stuart Galbraith doesn’t want to expand the Knebworth site too much to accommodate extra metalheads.

Organisers had to turn away Iron Maiden fans on the Sunday this year, but Mr Galbraith is reluctant to increase the UK leg of the tour too much above the 60,000-mark for fear of ruining the festival’s current friendly vibe.

Outlining his vision for the future, he added: “As to whether we will get bigger, I don’t want to see Knebworth get much bigger. I like it this scale.

“I think if we go much past 55,000 to 60,000 people we will start to lose the atmosphere.

“I’d much prefer to have an inclusive festival where we can camp the full capacity at the festival and have people here all weekend.

“One of the major differences we had this year from last year was that a good quarter of our audience arrived here on the Thursday.”

Planning is already well underway for the 2011 festival, which is scheduled for the final weeks of July, with the exact dates to be confirmed.

Despite the resounding success of this year’s three-day event, festival founder Mr Galbraith said: “We will always aim to be better.

“The day we sit here and tell you we’ve had a perfect festival is the day we should give up, as that’s impossible.

“We will learn from our good bits from this year and more importantly we will learn from the bits that didn’t go quite so well.”

On the festival effectively taking place in her garden, Martha Lytton Cobbold, managing director of Knebworth House, said: “It’s been a very smooth ride for us [this year] and we look forward to having it again next year.”