Child acts should be measured on a simple formula. Imagine them as adults and would they still be good.
Unfortunately, the majority of the child acts over any year would not be anywhere near this show if they were adults.
Today was the perfect example of either end of the scale. Jack & Cormack were very good, very talented, but for their age - as adults they'd have got 4 X's within 10 seconds.
Whereas Comedian Jack had he been an adult, had he been anything he's not, he'd still have been a terrific act, so is deservedly there.
You can do this for any year. George Sampson as an adult IMO would never have made it past the first audition whereas Shaheen would've walked it regardless of whether he was 12 or 42.