Seventy years ago, the NHS was established on a promise and a principle. The promise was that the service would be available to everyone free of charge at the point of delivery and the principle was that it would be financed entirely from taxation so that people paid into the service according to what they could afford. Seventy years on, the promise has been kept (more or less), and the principle still stands (on the whole). It is an achievement worth celebrating.

To mark the occasion, all this week The Herald will be telling the stories of some of the staff who have made important contributions to the service over the last 70 years. People like Gertrude Herzfeld, Scotland’s first practising women surgeon. Or Sir John Crofton, who led the fight against TB. Or Ronnie Stewart, who has only recently retired as a porter at Ninewells Hospital in Dundee - a job he started in 1969.

NHS at 70: Celebrating a revolution in Scotland's healthcare

It is the work of these men and women that demonstrates just how much the NHS has achieved in seven decades. When Sir John Crofton joined the service in the 1950s, it was common for TB patients to spend months in sanatoriums but our knowledge of this and most other conditions has dramatically improved. We are also better at prevention thanks to routine screening. And we have overcome taboos over contraception and abortion. It is an ongoing story of invention and progress.

The overwhelming majority of patients also appear to appreciate what NHS staff do - when asked, the majority rate their experience as good or excellent - although no one thinks the staff are perfect or that nurses and doctors are angels. The principles of the NHS are celebrated round the world - apart, perhaps, from in the White House - but it is a service that is created and run by humans for humans and that means that sometimes it goes wrong. That is not excusable - just inevitable.

Part of the problem is the daily pressure on staff. Many nurses feel stressed to breaking point, with the majority saying that they are worse off financially than they were five years ago.

NHS at 70: Celebrating a revolution in Scotland's healthcare

The staffing crisis is just as bad in other parts of the service too. There are not enough junior doctors to fill the jobs that need doing. There has also been a sharp increase in the number of vacancies in GP practices, the reason being that young doctors take one look at the stress and burden on GPs and decide it is not for them.

The pressures on the service are also coming from other directions, principally the country’s changing demographics and the fact that the number of over-85s is expected to increase 110 per cent by 2034. The NHS itself may be 70 years young, but it is not ready for that kind of change.

All of this has a direct effect on budgets. The staffing shortage means the use of locums to fill the gaps; NHS boards have also spent more than £38,000 a day on consultants’ overtime in the past three years for example. So-called bed blocking has also cost NHS in Scotland more than £360 million over the same period.

NHS at 70: Celebrating a revolution in Scotland's healthcare

Does this mean we should postpone the celebrations of the 70th anniversary? Of course not. But it is a good opportunity to finally face up to the changes that are needed to prep the service for the next 70 years. There are definitely signs of progress in integrating health and social care, but that will have to be completed effectively if the pressure on the NHS is to be reduced. We should also do much more to relieve the pressure on NHS staff and services by allowing pharmacists to take on more of the burden and employing more support staff for GPs.

However, in celebrating the men and women who work for the NHS, shouldn’t we also acknowledge the best present it could get for the 70th anniversary: an acceptance from government that it does not have the funding it needs?