Walk round parts of central London and you’d be forgiven for thinking it’s a city of young people. This blind spot extends to the unthinking way those without mobility impediments get around the stairs, tube escalators, barriers, broken paving slabs and high pavements that crowd our streets.

Yet for the 1.2 million Londoners with a disability, these streets are not a helpful pathway but an obstacle course that may be simply impossible to traverse. Despite the Mayor’s £200m extra investment to make the transport network more accessible, by 2022 still only 40 per cent of Underground stations will be step-free. The next time you are on the Tube, try planning your journey using only the step-free stations and you’ll understand the extra time and trouble this one aspect of a city, designed without equal use in mind, can cause.

It is not only those personally affected by a disability who are impeded. It’s also the hundreds of thousands of Londoners who provide unpaid care for their loved ones who may be too old, young, or unwell. As I set out in my report Who Cares?, these Londoners are a silent public service, and ever more of us are set to join their ranks in the coming years.

But many carers still find themselves disconnected from normal life. While looking after a loved one can bring great purpose to life, it is also a heavy burden to bear because the design of our city’s streets, homes and amenities is ignorant of alternative needs.

Despite the remorseless logic of an aging population with more complex medical conditions, and a threadbare social security net, 50 per cent of people who currently do not have a caring responsibility think it unlikely they ever will have one. As a city, we are not ready for the fact that many more people will find they have to look after someone. This is reflected in our urban planning, too.

We are currently marking Carers Week 2019, focusing this year on “connecting carers”. As any carer will tell you, going out with their charge can be a daunting process. Too often it is easier to stay in and avoid the rush and risk of bumps and trips, the pavements too narrow for a wheelchair, and the buildings that turn out to be inaccessible.

Yet our homes and housing policies are part of the problem too. Though new builds should meet certain accessibility standards, London has seen an explosion of small homes thanks to Permitted Development Rights, which allow office-to-residential conversions to dodge design standards. That is not to mention the state of our aging private and social housing stock. All in, we have too few suitable homes for the growing numbers of Londoners who need adaptations to keep living independently.

Let us not forget, two years on from the Grenfell Tower fire, that residents with mobility issues were living in flats high up in that block without an easy way to escape. At best, good urban design helps us live healthily despite old age or ill health. At its worst, the consequences for individuals are dire.

There are some signs that the picture is changing. Transport for London (TfL) is investing £2.3bn in the next five years in a world-leading programme to make our streets navigable for all. The mayor of London’s Health Inequality Strategy sets out new targets for accessible homes, followed up with tougher planning guidance in the New London Plan. And our efforts to become a dementia friendly city will pay dividends for many more Londoners than just those with dementia.

It cannot be right that an increasing proportion of London’s residents find themselves cut off. While planning for old age and disability may produce less exciting artists’ renderings than glassy new high-rises, it will make a more significant contribution to London’s future.

For too long, we have taken a “make do and mend” approach to how our cities are shaped to meet their citizens’ needs, leaving the NHS and individuals to pick up the pieces. Now, with the right political leadership from City Hall we have a chance to fix this. Changing demographics leave us with no other option.

Dr Onkar Sahota is a member of the London Assembly for Ealing & Hillingdon, a practicing GP in West London, and Labour’s London Assembly Health Spokesperson. He tweets as @DrOnkarSahota.