I'm not sure that it's even worth asking why Gordon Smart has run long-lens photos of Gary Barlow's kids ("Daniel, who is eight next month, and six-year-old Emily", as Gordo helpfully points out), because the PCC rules about children are pretty clear:
Editors must not use the fame, notoriety or position of a parent or guardian as sole justification for publishing details of a child’s private life.
So there must be some strong reason for this intrusion into the preeteen's privacy, right?
Erm... their mum is pregnant. Well, you can see why you would want to ignore PCC rules on children and privacy under those circumstances - who can enjoy the prospect of an expanding family without having creepy shots of their kids taken from across the street being slapped alongside Sienna Miller's topless hugs, eh?