Ray Thomas, founding member of the Moody Blues, has died suddenly at the age of 76.
The flautist and vocalist died on Thursday, his record label confirmed in a statement.
"It is with profound sorrow and sadness that Cherry Red Records and Esoteric Recordings regret to announce that Ray Thomas, founder member, flautist and vocalist of the Moody Blues, passed away suddenly at his home in Surrey on Thursday 4th January 2018.
"We are deeply shocked by his passing and will miss his warmth, humour and kindness.
"It was a privilege to have known and worked with him and our thoughts are with his family and his wife Lee at this sad time."
Born in 1941 in Stourport-on-Severn, Thomas formed The Moody Blues alongside Mike Pinder, Denny Laine, Graeme Edge and Clint Warwick.
The group enjoyed huge success during the the 1960s and 70s, with hits including Nights in White Satin, Go Now and Question, and selling more than 70 million albums worldwide.
Thomas also had a successful solo career, releasing several albums. In 2014 he revealed he was battling prostate cancer, having being diagnosed the year before.
"My cancer was in-operable but I have a fantastic doctor who immediately started me on a new treatment that has had 90% success rate," he wrote on his website.
"The cancer is being held in remission but I'll be receiving this treatment for the rest of my life."
The Moody Blues, including Thomas, were set to be inducted into the Rock & Roll Hall of Fame in 2018