School source says the policy has been in place for about six months

The thieves believe the students will be carrying expensive smartphones

A number of students have been targeted and mugged by criminal gangs

Boys at St Paul's have been banned from wearing blazer outside gates

It is one of the most prestigious public schools in Britain, with the distinctive black blazers of its pupils a familiar sight in the West London borough of Hammersmith.

But because of a worrying wave of street robberies in the area, the boys from St Paul’s School have been banned from displaying their uniform outside the school gates – and parents at the £22,000-a-year establishment have been urged to buy hooded tops for their sons so they blend in more easily with the local youths.

It is understood that criminal gangs have been targeting the pupils in the belief that they are likely to be carrying expensive smartphones.

The mother of one young robbery victim said: ‘If anything, they could get into trouble with teachers for keeping their uniform on these days. The mugging problem has become very bad lately. There have been at least 14 that I know of.’

Students at St Paul's School are being targeted by criminals as they believe the pupils will be carrying expensive smartphones

St Paul's School (pictured) is a £22,000-a-year establishment near Hammersmith, London

The concerned parent said teachers now patrolled Hammersmith Bridge because most pupils have to walk across it every day and the muggers wait at either end knowing they have no escape.

‘They know these children have the best iPhones or the best laptops and iPads,’ she added.

The boys-only day school on the banks of the Thames has one of the toughest admissions tests in London and most pupils come from its £6,000-a-year preparatory school Colet Court. Former St Paul’s pupils include the poet John Milton, diarist Samuel Pepys and Chancellor George Osborne.

The rules state that boys are required to wear charcoal grey trousers with a plain white shirt and a school tie corresponding with their house for most of the time, adding the famous black blazer for formal events.

Chancellor George Osborne (pictured) is a former student at the school

Now they have been told to cover up the ties and are also allowed to exchange their black leather shoes for trainers to walk home in.

And although many former students wear their St Paul’s School scarves with pride, current pupils are told they could be putting themselves in danger by following suit in public.

It seems the recent spate of robberies might not be an entirely new phenomenon.

Former pupil Douglas Edwardes-Ker, now 30, told The Mail on Sunday last night: ‘There were some muggings in my day. The bigger kids like me would look out for the smaller ones and try to save the day if something went wrong.

‘The local kids from the estates nearby hated us. They saw us as privileged and spoiled and I suppose they thought we were an easy target because they assumed we wouldn’t fight back.

‘They didn’t account for some of the rugby players.’

A school source said the no-uniform policy had been in place for six months, and in that time, the number of muggings had fallen significantly.