The NHS reached its 75th birthday in July but for how much longer can it continue in its current form.
When the NHS was created the main focus was on short bouts of treatment for injury and infection, but now the challenge is completely different.
The ageing population means huge numbers of people are living with chronic health problems, such as heart disease, dementia and diabetes that require long-term care and for which there is no cure.
It is already estimated that about £7 out of every £10 spent in the NHS goes on people with these conditions. On average, those over 65 have at least two.
And the situation is only going to worsen. "The numbers are going to grow," Health Foundation director of research and economics Anita Charlesworth says as the baby boomer generation is reaching old age.
The amount of public money spent on the NHS has been rising ever since the health service was created and it now accounts for more than 40p out of every £1 spent on day-to-day public services and many are asking whether such spending is sustainable.
Former Health Secretary Sajid Javid, who has floated the idea of charging to see a GP, arguing the NHS should be willing to learn from the approaches adopted by other countries, has called the current direction of travel "unsustainable".