Schools in London have been transformed since the late 1990s. Our state schools have seen enormous improvements as a result of the London Challenge programme, launched in 2003, and the huge investment in new schools and school leadership in the late 1990s and noughties.

London now has more good and outstanding schools than in any other region and has become an international beacon for education - leading the way in narrowing the achievement gap between children from rich and from poor backgrounds. This is something that we should be proud of, but I’m increasingly worried that the progress we have made is being put at risk.

I’m increasingly worried that the progress we have made is being put at risk

At a time when our schools are already dealing with looming budget cuts, the government has chosen to hit London’s children the hardest with its new funding-formula proposals. With these controversial proposals, 70 per cent of London schools face a reduction in funding, which comes alongside the threat of an 8 per cent shortfall per pupil by 2019-20.

The London schools system is already financially fragile and these additional funding pressures could really cause our schools to struggle. But this is not the only unfair and regressive education policy that the government seems adamant on implementing - they also want to increase the number of grammar schools across the country.

This twin attack - the combination of reducing funding for our schools and reintroducing selective education - could well undo all the progress we’ve made in recent decades.

Some of the grammar schools we have in London are great schools - no one is disputing that. But the answer to the problems we face in the education system is not to spend more money on opening yet more selective schools.

Cash boost worth paying

Opening new grammar schools was the wrong policy before and it’s still the wrong policy; it will not only make it harder to ensure that every child is able to fulfil their full potential but it will also guarantee that some children are left behind.

So, as the mayor of London, I’m opposing the expansion of selective schools and fighting for a fair funding system. London Councils, the organisation that represents the 33 boroughs in the capital, estimates that only £335 million extra would ensure that no school across the whole of England would lose out with the new funding formula. This is a relatively small amount in terms of the education budget and would be an investment worth paying - because a high-quality, fair education system is one of the best investments that we could ever make as a country.

Last month, at my first Mayor’s Education Conference at City Hall, I also published my Annual London Education Report. This confirmed our success in supporting vulnerable and disadvantaged pupils, but it also highlighted that inequality is still an issue for many children in London.

Improving early years education will be absolutely key to tackling this, because the gap between disadvantaged children and their peers starts early and only increases as they progress through school. That’s why my deputy mayor with responsibility for education and childcare, Joanne McCartney, is focusing on improving early years education, and making childcare more affordable and accessible to all parents.

We’re also working at City Hall to ensure that we have enough childcare facilities and school places across our city. And we’re focusing on high-quality apprenticeships, particularly helping girls and pupils from minority backgrounds into the science, engineering and technology sectors. This will not only create new opportunities for many Londoners, but help to fill the large skills gap we have across London.

The report also addresses one of the biggest problems at the moment in the education system in London, which is that many teachers are being put off from working and staying in the capital owing to the high cost of living.

Background should be no barrier

Excellent teachers are the backbone of our education system and from personal experience, from seeing my two daughters go through school and from being a governor for more than 20 years at the primary school I attended as a child, I know that great teachers make an enormous difference.

There’s no doubt that without inspiring teachers, I wouldn’t be where I am today. For example, it was my headteacher, Naz Bokhari - an outstanding teacher and a role model for me and thousands of other children at Ernest Bevin College - who encouraged me to go to university and aim to put something back into society. He made me realise that skin colour and background should never be a barrier to fulfilling your potential.

My aim is to form a real partnership with teachers to ensure that the progress we have made in recent decades is not squandered

The work teachers do every day makes a big difference - the difference between success, failure and the life chances of the young people they teach. So at City Hall, we are committed to supporting them by making it easier and more affordable to be a teacher in London, improving professional development and properly nurturing our potential teaching talent.

In the weeks ahead, my education team will be talking to teachers and headteachers, so that they can feed into our ambitious new vision for education in London, which will help steer our work with schools, London’s boroughs and the wider education system. My aim is to form a real partnership with teachers to ensure that the progress we have made in recent decades is not squandered and to ensure that everyone in London can get the education that helps them reach their potential - the education they deserve.

Sadiq Khan is mayor of London
@SadiqKhan