Judy Murray, the mother of ATP players Andy and Jamie Murray and Britain’s Fed Cup captain, tells The Guardian that juniors need to mix up their competition.

“When Jamie and Andy were eight and nine they were playing with a normal tennis ball on a normal-size court, and doing pretty well,” she said. "They were playing not just for the under-12s and junior local team, but with grown men, some of the old fogies at the [Dunblane] club. They were learning how to play the game properly. Kids can get stuck far too early in their own age group.

"If they were eight and nine now, they would not be allowed to be play with a yellow ball, on a full-sized court or in an under-12s competition. A lot of stimulation for them at that age was that there was a big variety of competition for them. That is not the case now.”