To see the pain those children were in and witness the traumatic impact on their families was absolutely heartbreaking.
But something else has stayed with me from that visit, too. For there, in response to the worst that humanity could do, I saw the very best.
Theresa May visited Royal Manchester Children’s Hospital in the aftermath of the Manchester bombing earlier this year
I met paramedics who had raced to the scene, thinking nothing of their own safety but only of the safety of others. I met inspirational doctors and nurses who had been working 24-hour shifts to treat the injured and save many lives. And I spoke to the families of those being treated, who told me about the extraordinary care their loved ones were receiving.
So alongside the horror and anger over what had happened in Manchester, I felt once again that deep and overwhelming sense of pride we all share in our National Health Service — and a humbling gratitude for the incredible people who work within it.
I felt the same on the visits I made to hospitals in London in the aftermath of the Westminster and London Bridge terrorist attacks, and after the devastating tragedy at Grenfell Tower.
In every instance, what struck me was not only the medical expertise of the staff, but the compassion with which people were treated and the way the NHS, in an emergency, clicks into action.
Prime Minister Theresa May visits fourteen year-old Evie Mills, from Harrogate, North Yorkshire, who was seriously injured in the Manchester Arena suicide bombing
People who weren’t on shift came in, others stayed long after their shift was over, not because anyone had asked them to, but because they knew something serious was happening and they wanted to help.
I know that the feelings of admiration and gratitude we have for all those working in our NHS are felt by thousands of families in hospitals and surgeries up and down the country, 24 hours a day and seven days a week.
For time and again, the NHS gives true meaning to our belief that access to healthcare should be based on need, not on the ability to pay.
And time and again, it is those in our health service who embody that spirit, going above and beyond the call of duty in caring for our loved ones and comforting us in some of life’s most difficult moments.
So I am delighted that the Daily Mail is once again honouring our national Health Heroes with a nationwide search for the most inspirational acts of kindness and compassion from people in all parts of our NHS.
From the surgeon in the operating theatre to the nurse visiting first-time parents in their home; from the GP receptionist to the volunteer at a community mental health cafe, the Health Hero Awards will honour all those whose work and selfless dedication make such a difference to our lives, yet all too often goes unrecognised.
I know from my own experience what a difference our doctors and nurses can make. After being diagnosed with type 1 diabetes, I was referred to clinical nurse specialists.
Nurse specialists work closely with doctors, nurses and other healthcare professionals to help improve the understanding of a range of conditions and their treatments, from diabetes to Parkinson’s to arthritis.
Prime Minister Theresa May (right) meets nurses, during her visit to the Renal Transplant Unit at the Royal Liverpool University Hospital
These nurses were attached to the local hospital and in the early days, as I was adjusting to the new treatment regimen, having the comfort of knowing there was someone I could pick up the phone to, and who could give me advice, was really reassuring.
I’m a great believer, with these long-term conditions, in as much self-management as possible, and to have someone who can give you that expertise is really helpful.
It is the reassurance that nurse specialists provide which is key. And it is this reassurance, this care, this compassion that is in the DNA of our NHS.
That is why, over the past 70 years, it has become one of our most loved institutions, indelibly written into the identity of our nation.
As we saw in the unforgettable opening ceremony of the London Olympics in 2012, it is part of our statement to the world about who we are and what we believe in.
So let us celebrate our NHS with pride and recognise it for the extraoardinary institution it is.
Day in, day out, we know that if we are in an emergency situation and need that care from the NHS, it will be there — and that the people who work within it will do their very best for us.
I hope you will continue to show your appreciation and share your stories by nominating your Health Heroes in the coming weeks.
And I look forward to welcoming the winners to Downing Street in December.