“I don’t think it’s correct at all,” said the first coach. “Many calls seem wrong. Bring back umpires and the challenge system.”

The other coach told Telegraph Sport that he had noticed a significant difference in the performance of ball-tracking systems on the various surfaces. “When we play on hard courts, nobody ever has an issue,” said the coach. “On clay, there may be more room for debate, because it’s a shifting surface and the granules move.

“But on grass this summer, I’ve really noticed a lot of calls that just look wrong. You can see it from the body language of the players because they hesitate for a moment when they see where the ball has landed. I don’t know why it’s happening so much, but I think the cameras like the ground to be completely level and that’s not always the case, particularly around the baseline after a few days’ wear and tear. I’ve also heard it suggested that the grass grows a small amount each day and that affects the calibration.”

The recent introduction of ELC as the sole arbiter of Wimbledon line calls has provoked other complaints. One deaf tennis-lover wrote to the Lawn Tennis Association to say that they can no longer tell whether a ball was in or out without the hand signals formerly used by the line judges: arm out wide for “out” and palms down for “in”.

Even for those with good hearing, it was hard to pick up the automated voice calls on Centre Court during Raducanu’s thrilling match against top seed Aryna Sabalenka. Not only was the crowd constantly buzzing with excitement, leading to a slight background murmur, but the closing of the roof added to the swimming pool-style hum.

Meanwhile, on the outer courts, Ben Shelton’s match against Rinky Hijikata was suspended at 9.29pm on Thursday – despite Shelton standing just one game short of victory – because the light was declining to the point where officials feared that ELC would not be able to function. Shelton was so frustrated by the decision that he had to be held back from extending his argument with the chair umpire by supervisor Ali Nili.