A festival has released the names of two of its main headliners.

British heavy metal band Iron Maiden and American rock group Metallica will both play Sonisphere on the grounds of Knebworth House in July.

This will be the first time both have appeared on the same festival bill in this country.

A spokesman for the festival said: “During our two year absence we’ve continued to believe in and work hard on Sonisphere. We said in 2013 that if we had the right line up then we would be back, and that’s exactly what we’ve got in 2014. The omens were obviously on our side when we secured the two biggest and best metal acts of all time in the year that also brings the 40th anniversary of the first concert at Knebworth.

“Our excitement at being able to offer Metallica and Iron Maiden on the same bill for the first time ever has been hard to contain. To do so in a year of great celebration for the iconic venue is very satisfying. Sonisphere 2014 is going to be a legendary year.”

Sonisphere will return from July 4-6 with the festival celebrating 40 years of rock at the iconic outdoor venue.

Tickets are on sale now via the Sonisphere website http://sonisphere.co.uk/