A few days after my daughter was born, she nearly died. During this time, she had to wait for hours on a ward at Whipps Cross hospital in east London, just to see a doctor.

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One morning amid this ordeal Boris Johnson visited the ward my daughter was staying on during his trip to the hospital. Sightings of doctors and nurses on that ward had been rare previously, but suddenly they were everywhere – while the floors sparkled and flowers decked the corridors.

Seeing this triggered almost primeval feelings about my child’s treatment: I confronted the prime minister in front of the cameras of the national media about my daughter’s care and the wider state of the NHS.

What happened next is probably best watched rather than recounted here. Safe to say, I gave the prime minister a piece of my mind. My thoughts were soon echoed by various staff and patients at Whipps Cross.

In the aftermath, much was made of the fact that I am a Labour activist. That’s something I am proud of. But my decision to speak to Johnson in that moment was based on how my daughter had been treated, as well as my own personal values.

The experience of my daughter’s near-death and her neglect in hospital brought back memories of a particularly formative and painful moment: in October 2000, I sat by my grandmother’s bed as she neared the end of her life at Alexandria University hospital in Egypt. The hospital was dirty and poorly equipped. The nurses were uncaring, perhaps knowing that my grandmother would shortly die, which she sadly did. That experience was harrowing and life-changing.

For as long as I can remember I have been interested in politics, but being with my grandmother when she died was what turned me into a political activist. I left the hospital vowing to myself that one day I would help rebuild it, so others did not have to go through the same experience that she had. Returning to Britain, I also joined the Labour party and threw myself into campaigning on all kinds of social issues. I had a fairly privileged life, but it was the experience with my grandmother that made me realise that nothing can be taken for granted and that everyone should be guaranteed dignity – in life and death.

After my encounter with the prime minister – and the media attention it received far and wide – the chief executive of Whipps Cross, Alan Gurney, visited our daughter’s room every day. He told me that the hospital badly needed a complete rebuild – which chimed with my experience of Whipps Cross.

The site is huge, with a portering system that is clearly struggling, and doctors are forced to run between different wards that they need to cover at the same time, far apart from each other. Whipps Cross’s inferior facilities make it difficult for it to compete with other hospitals for staff, and deter patients from using it. The chief executive said that there were plans for redevelopment, but that approval and funding was needed from the government.

A few days after my encounter, the prime minister announced funding for a complete rebuild of Whipps Cross and other hospitals. Great news; except it is unclear exactly what the government has approved, and when the money will be available. Furthermore, only a few hospitals out of the many that need redevelopment will be receiving committed funding. The government’s announcement covers less than 10% of the extra money that health experts say is needed for new buildings and equipment. I am amazed that Johnson seems so proud of massively underfunding the NHS.

Whipps Cross is just one example of how our NHS is literally falling apart: hospitals are crumbling, equipment is broken and repairs are not being made. Spending on buildings and equipment is insufficient to meet the NHS’s needs – this means hospitals will struggle to continue to provide the current level of service.

Over the past decade of austerity and cutbacks, money that should have been spent on NHS equipment and buildings has been diverted by the government to be used for day-to-day NHS running costs, such as paying salaries. There is a £6.5bn maintenance backlog. The risks to patients of this underinvestment are rising day by day. What does this mean in practice? One director of an NHS trust has described how broken gutters in his hospital lead to water seeping through the walls when it rains heavily. This has become so serious that staff have to unplug electrical equipment – including the incubators for newborn babies.

Because of this crisis, I am launching a campaign for the government to provide the funding needed to remove the maintenance backlog and make sure that the money needed is in place for NHS buildings and equipment. If there is a general election in December, that is something all parties should be committing to.

When I confronted Boris Johnson in September, I was angry about my daughter’s treatment – but nothing I said to the prime minister was meant to undercut the dedication and commitment of the staff at Whipps Cross. The people working in A&E literally saved her life. All NHS staff deserve to work in good conditions and to have the equipment they require to do the best job they can. Patients too deserve decent hospitals, with safe, functioning infrastructure and equipment. We need to rebuild the NHS.

• Omar Salem is founder of Rebuild Our Health Service