TICKETS for this summer’s 2011 Sonisphere Festival at Knebworth House are selling much faster than last year.

The three-day rock event returns to the grounds of the Hertfordshire stately home from Friday, July 8 to Sunday, July 10.

And festival mastermind Stuart Galbraith told Amplified TV in an interview this week that ticket sales for Knebworth are “60 per cent up on this point last year”.

This follows an earlier warning from organisers that day tickets might not be available for Knebworth this summer.

Thrash metal’s Big 4 of Metallica, Slayer, Megadeth and Anthrax will perform together on the same bill for the first time in the UK on the opening night.

Scottish rockers Biffy Clyro will headline the Saturday, with the line-up also including Weezer and Watford punks Gallows.

Iowa metallers Slipknot will close the festival on the Sunday with their first performance in this country since the tragic death of bass player Paul Gray.

Nu-metal faves Limp Bizkit will be the day’s special guests.

Galbraith said in the Amplified interview: “With regards to tickets sales, Knebworth and most of the other Sonispheres throughout Europe are ahead of the sales patterns that we had last year.

“Knebworth is 60 per cent up on this point last year and I think we’re actually heading for our first ever sell out.”

Sonisphere organisers had to turn away at the gates Iron Maiden fans looking for day tickets on the closing Sunday afternoon last year.

And a statement posted on the international touring festival’s UK website yesterday (Thursday) under the banner ‘Sonisphere Sells Out (ish)’ says: “Okay so we were going for the shock headline there and we apologise for any panic felt by those with a sensitive disposition.

“You can still get hold of three and four day festival tickets but the cold hard facts are that we are starting to sell out of some of the ticket types for this year’s Sonisphere, all ticket types are selling much faster than last year, and we thought we had better give you the heads up about that.

“Already sold out are campervans, yurts and podpads and on the hotel packages we are down to a couple of rooms at the Novotel (the one almost on the site) and the Hanbury Manor (the really posh one).

“This is just a nudge for those who might be confidently sat around thinking you have plenty of time to wait for pay day, your mate Dave to make his mind up or your boss to give you the time off.

“Don’t leave it too long and miss the chance to say you were there when the Big Four walked onto a UK stage for the first time in history.”

Last summer’s second Sonisphere spectacular attracted in the region of 35,000 for the new Friday night of music headlined by shock-rocker Alice Cooper.

More than 50,000 packed into the arena on the Saturday for German industrial metallers Rammstein’s explosive main stage performance.

And there were 55,000 plus in Knebworth’s grounds for Iron Maiden’s only UK performance of 2010.

A three-day camping pass for Knebworth 2011 costs from �180, with four-day camping tickets starting from �190.

For more information on Sonisphere and Knebworth ticket details, go to the festival’s website.