Secondary schools are introducing strict new bans on mobile phones where all pupils aged up to 16 have to lock them away for the entire day after evidence that it makes children more sociable, alert and active.

From September pupils aged 11 to 16 who own phones at the schools will be required either to hand them in or put them in their lockers when they arrive for registration and only get them back when they leave in the afternoon.

The sea-change in approach coincides with an appeal last week by culture secretary Matthew Hancock in The Daily Telegraph for schools to ban smart phones during the school day. It comes as this newspaper campaigns for a legal duty of care to protect children from digital harms.

Typical is Latymer Upper school in west London where its ban on phones is to be extended to all children up to the end of their GCSE years after its success in restricting access to younger pupils.

The independent school said its ban on mobile phones for pupils aged 11 to 13 had been “incredibly positive” with an increase in children playing outside, attending clubs and societies and socialising with each other.

From September all pupils from 11 to 16 will have to switch off their phones and put them in their lockers from 8.25am to 4pm with parents told they should ring the school if they need to contact their sons or daughters.