If the government really wish this to happen, then they need to put their money where their mouth is. I have just started maternity leave from a job promoting walking and cycling to school, there is a fund called the local sustainable transport fund, and the whole idea is to reduce congestion on the roads in towns and cities to ensure that they remain attractive places for businesses to invest.
The main issues stopping parents walking to school are, that they need to drive to school and go straight to work afterwards.
However, parents also do not walk because of fear for the safety of their children, many schools do not have school crossing patrol officers, and who can blame people for not taking a role which is for most borough councils the lowest paid one on the whole of their payroll.
To put this in place and make it workable, there would need to be a safe place to drop children, for parents to then go straight onto work, and then for school staff to ensure children get to school safely, via walking buses. So called park and stride sites.
There should be school bus services that parents can book their children onto, where they are certain they will be safe for the whole of the journey.
All those that are not going to work, should be targeted to try to persuade them to walk to school.
If the government want to stop parents driving to school, the alternatives need to be attractive, and fit with parent's needs. People used to walk their children to school, but most couples had one parent staying at home and available to walk them to school.
The funding I spoke of above is woefully inadequate and will for some boroughs run out at the end of this financial year. It does not cover all schools but only a select few.
Times have changed, arrangements for getting to school need to change too.