Friends of Sir Cliff Richard have criticised police for taking more than a year and a half to investigate a claim of sexual abuse against him. The 75-year-old singer has now been under investigation for more than 540 days, ever since South Yorkshire Police raided his home in Berkshire in August 2014, live on the BBC.

The investigation resulted from a claim that Sir Cliff abused a man in 1985 in Sheffield, during a rally for American evangelist Billy Graham. The artist strenuously denies all accusations against him.

According to the Sunday Mirror, the case has still not been sent to the CPS after 19 months. Friends contacted by the newspaper, including Paul Gambaccini, who has himself been cleared of historic abuse claims, have now said that they believe Sir Cliff is innocent and that the case should be closed.

The BBC broadcaster, 66, said: "If Cliff is ever convicted of offences, down to and including traffic violations, I will eat my hat. None of his friends believe a word of what the South Yorkshire Police are peddling."

He added: "This case is a disaster for Great Britain. Sir Cliff is one of the greatest Englishmen of the 20th Century and has been persecuted in one of the greatest scandals of the 21st Century. This is a historic scandal."

The singer is currently holidaying in Barbados and is gearing up for a season singing on cruise ships. Another close friend, David Wigg, told the Mirror that the delay was "really employing".

"As far as I'm concerned Sir Cliff has had an unblemished life," he said. "I don't believe any of these accusations. I don't understand why this is taking so long. I think it's awful for him and it's been a tremendous strain not having any conclusion."

After the singer returned to Britain in November to meet with police, his spokesman said in a statement: "Sir Cliff Richard voluntarily met with and was interviewed by members of South Yorkshire Police. He was not arrested or charged, nor has he ever been. He cooperated fully with officers and answered the questions put to him.

"Other than restating that the allegations are completely false and that he will continue to co-operate fully with the police, it would not be appropriate for Sir Cliff to say anything further at this time."

In a statement released to the Sunday Mirror, South Yorkshire Police said: "The investigation continues and we are now receiving investigative support from the Crown Prosecution Service."