‘An amazing person and I was very proud of him,’ writes PBO reader Chris Prow, paying tribute to his son, one of the two workers killed setting the stage for a Madonna concert in Marseilles, southern France on Thursday, 16 July.

‘My son Charles was tragically killed last Thursday, aged 23. He was part of the crew building the stage for the Madonna concert in Marseilles when the roof collapsed.

‘I remember the first time i took him sailing. I cut the engine and the wind filled the sails and he shouted: “Dad! Dad! I can’t believe it – we’re sailing!! – its fantastic!”.

‘The look of sheer unadulterated pleasure on his face is something that will remain with me forever.’

Charles from Headingley, Leeds, went on to qualify as an Ocean Yachtmaster. He and his father bought an old Achilles 24 which they repaired together and sailed.

‘The last trip when we sailed her from Hartlepool up to Amble Marina is a memory I always will treasure,’ Chris said.

Madonna described the deaths of Charles and 53-year-old Frenchman Charles Criscenzo as “a great tragedy”.

French police have launched a manslaughter inquiry.