'Imagine telling a child to walk to school across this on his own," says Louise Balcombe with a shake of the head as she waits to ease her people carrier into one of six lanes of traffic. Finchley Road cuts through Hampstead like a Berlin Wall perpetually being remade from the exhaust fumes of cars, lorries, taxis and buses. We are leaving the comparatively modest streets bordering Cricklewood, where Mrs Balcombe lives, and crossing over to the leafy lanes of Hampstead proper, where her sons go to school.
Twice a day this comfortable part of north London becomes one of the worst traffic spots in the country, immobilised by the curse of the school run. There are 30 schools within a mile of Hampstead tube station, and the majority of the 8,000 children they educate are transported by car.
Hampstead may be posh but its parents are not unusual. The number of children in Britain being driven to school has doubled in the past 10 years, and the percentage of those who walk has halved. Parents are more fearful than ever that their offspring will be abducted by paedophiles, mugged for their mobile phones, stabbed by street gangs, or fall into bad company on the way to the school gates.
The irony is, of course, that the busier the roads become the more dangerous they are for those youngsters who do walk. And now that research has confirmed the link between car fumes and asthma, there is growing concern about the number of vehicles congregating outside schools in the morning and afternoon. Even parents who remove themselves to the countryside for cleaner air find they have even less choice, believing they need to drive their children to school – and then end up surrounding the playground with fumes.
Pedestrians are not the only ones affected: when a car is in traffic the pollution levels inside can be 10 times worse than those outside on the street.
"There is a huge problem here," says Mike Greene, the councillor in charge of trying to solve Hampstead's school run blight. "The area comes to a grinding halt for three-quarters of an hour. Cars are almost stationary, engines turn over pumping fumes into what would otherwise be clean air up here on the hill. Few of them take more than one child."
The Conservative councillor describes himself as "blue with lots of green streaks", which may be why he chairs the council's traffic inquiry. It has just finished hearing six weeks of evidence from schools, parents, community groups and experts, including a video nasty of a typical school run.
Mr Greene notes the parking on "the zig-zag lines outside schools, on double yellows, at bus stops, and over the entrances to playgrounds and car parks". Parents are given a "period of grace" notice they can put in their car window allowing them to park in resident bays for 10 minutes. "This has been used – and abused – extensively," says Mr Greene. "I have certainly seen parents sit there for up to an hour reading a book or a newspaper, with the engine going the whole time. We have also had physical and verbal assaults on traffic wardens."
The London borough of Camden, which covers Hampstead, is considering ways of reducing traffic, making the streets safer and public transport more efficient. It has even been suggested that teachers may have their car-parking spaces taken away to make room for mini-bus drop-offs – but that would be hugely unpopular with the increasing numbers of school staff who cannot afford to live locally.
There are no official school buses in the area but one company does operate a pick-up and drop service. This costs £45 a week for each child. "We just can't afford that," says Jeremy Balcombe. "Many parents have scrimped and saved to get their children into independent schools in the first place."
Public transport is not an option, adds his wife as we pull up outside St Anthony's, a Roman Catholic school where two of the couple's sons, Tristan, 10, and Sebastian, eight, are pupils. We are also picking up their friend Daniel, eight, whose father does the opposite school run on his way into central London in the morning.
"The journey is 1.8 miles as the car goes," says Mrs Balcombe. "Otherwise we'd have to get the bus to West Hampstead station, go one stop to Finchley Road and get another bus into Swiss Cottage and back up the hill again. It would take forever. The only alternative is a tube all the way into London to change and come back out. It's ridiculous."
The Balcombes are aware of the impact the school run may have on their sons and the environment, which is why they car-share. "We would love to do this another way if we could," says Mrs Balcombe. "But there just is no choice."