This month I celebrate 10 years as chief executive of Luton and Dunstable Hospital. For the first few years, I concentrated on building an environment of trust and respect between managers and doctors.

I was growing in confidence and we created a unifying mission: "Building pride in the L&D".

We also began a journey of continuous improvement, employing techniques being pioneered in other industries to support change and focus on patient safety throughout the organisation. This approach was characterised by ensuring a consistency of purpose and the stability of the executive team over a six-year period.

With all the structural changes over the past decade, how many NHS organisations have the same leadership now as five years ago, and does it matter? Those who study highly successful organisations suggest that it does. General Electric, one of the world's most admired corporations, has had just 12 chief executive officers in its 123-year history.

However, it is clearly not just time in post that makes the difference in transforming organisations. In his book Good to Great, Jim Collins defines a particular style of leadership, which he calls level five. He explains eloquently: "Executive leaders build enduring greatness through a paradoxical blend of personal humility and professional will."

It is these leaders' resolve and fanatical drive to achieve results, not for themselves, but for the organisation, that appears to make the difference. Those quoted in Good to Great are not larger-than-life, charismatic, high profile individuals; they are often self-effacing and shun the limelight, preferring to concentrate on doing what needs to be done to transform their organisation.

An unwavering focus on continuous improvement requires an injection of new thinking from time to time. One way of doing this is to bring in people who might be described as "positive deviants" - they know how to rock the boat without falling out.

At Luton and Dunstable, we have recognised the need to devolve autonomy through creating strategic business units, even though to date, our former, more centralised way of operating has stood us in good stead, having achieved foundation trust status and financial stability. We have shown consistency of purpose in our driving ambition for the organisation to lead the NHS in patient safety and setting ourselves stretch goals that go way beyond national targets.

The third phase of NHS reform in the 10-year plan is said to be transformation. Stability in leadership, personal humility and will, combined with a drive for continuous improvement, are key to successful transformation, but the NHS seems traditionally not to have valued them.

Chief executives who move on every two or three years cannot possibly achieve transformation - turnaround maybe, but not sustained high performance in which all members of staff are engaged and energised.