A Sea Cadet froze in horror when international-renowned concert pianist John Briggs knelt down in front of him and pulled down his trousers, saying: “Let’s have a look at you,” it is alleged.

The former member of Keighley Sea Cadets told a jury at Bradford Crown Court yesterday: “I froze solid and I knew this was not right.”

He said Briggs, who was president of the cadet group, indecently assaulted him at the pianist’s home in East Morton when he went round to do odd jobs more than 20 years ago.

The man said Briggs took him into a room with a “fancy couch”, got down on his knees and pulled up his shirt to look at his torso. He then undid the teenager’s trousers, pulled them and his underpants down and touched his private parts. The complainant said he felt like he had seen a ghost: “You freeze and you can’t speak.”

He told the jury he said “no” to Briggs, who replied: “Don’t worry, don’t worry. You’re with Uncle John.”

The witness alleged Briggs ushered him to the sofa and tried to push his hand down his pants. He wrote down what Briggs had done to him and gave the account to his mother.

She called the police, he gave officers his version of events but that was as far as it went. The man said he was about 16 at the time and Briggs was “a big fat man, very tall.”

He said he left the Sea Cadets after the incident. He later moved away from the area and the police contacted him in 2011 about the allegation he made in the early 1990s. The man’s mother told the court her son came back from Briggs’s home in a horrible mood and wrote her the note.

She recalled it saying Briggs admired the boy’s “bicycling legs” and shut the blinds with an electric remote control.

Briggs, 65, of Little Lane, East Morton, denies ten allegations involving two former piano students and three former members of Keighley Sea Cadets. The nine charges of indecent assault on a male person and one of indecency with a child cover a 25-year period beginning in the late 1960s.

The trial continues.