Celebrated conductor set to perform at the Proms is accused of punching a singer during a performance ‘for leaving the stage on the wrong side’

A celebrated conductor who is set to perform at the Proms has been accused of punching a singer during a performance.

Sir John Eliot Gardiner allegedly attacked William Thomas, 29, while conducting an opera in southern France on Tuesday.

Classical music website Slipped Disc reported Sir John – a close friend of King Charles – was annoyed Mr Thomas exited the podium on the wrong side after the first part of the performance at the Berlioz Festival.

He is said to have told off the singer backstage in front of the rest of the cast before slapping and punching him in the face. 

The BBC are investigating the reports ahead of Sir John’s scheduled performance at the Proms on September 3.

A source close to Sir John said the scorching 39C heat in La Côte-Saint-André had affected his behaviour

A source close to Sir John said the scorching 39C heat in La Côte-Saint-André, near Grenoble, had affected his behaviour, along with a recent change in medication. 

The 80-year-old is thought to have left the town soon after the alleged incident to return to Britain to see his doctor. His assistant, Dinis Sousa, reportedly took up his place for a following performance.

Sir John, known to his colleagues as ‘Jiggy’, has previously provoked criticism in the industry for his exacting standards and desire for control.

In an interview with the Financial Times in 2010, he said: ‘I can be impatient, I get stroppy, I haven’t always been compassionate. I made plenty of mistakes in my early years.’

He reportedly failed to land the job as musical director of Opera North because the musicians refused to work with him. 

And during his time with the London Symphony Orchestra, he was reported to have become furious with a brass player.

Despite this, Sir John is believed to have struck up a friendship with King Charles after meeting him at an event in Sandringham due to a shared love of organic farming and music.

Sir John, known to his colleagues as ‘Jiggy’, has previously provoked criticism in the industry for his exacting standards and desire for control

The conductor lives on and manages a 500-acre organic farm in north Dorset which was established by his great uncle, the composer Henry Balfour Gardiner.

Speaking of his friendship with the King, Sir John told the Telegraph: ‘For his 50th birthday I gave him a couple of breeding heifers, and when he knighted me in 1998, he leant forward and whispered, ‘Thanks for the heifers.’

Sir John contributed to the musical accompaniment at King Charles’ Coronation, conducting the orchestra during the arrival of guests at Westminster Abbey.

Tuesday’s alleged incident occurred midway through a performance with the Monteverdi Choir, which Sir John founded in 1964. The choir is still scheduled to perform in Austria and Germany before heading to the Royal Albert Hall for the Proms.

A BBC spokesman said yesterday: ‘We take allegations about inappropriate behaviour seriously and are currently establishing the facts about the incident.’ Representatives of Sir John and Mr Thomas were contacted for comment.