The average life expectancy for the homeless is shockingly low. Once Professor Aidan Halligan, director of education at the University College London Hospital, discovered how physical and mental ill health and addiction affected the homeless, he decided to act. He recalls: "The most vulnerable weren't getting the health service that they needed. The average age of death for homeless people is 40.2 years. That's appalling."

Halligan started a health service for the homeless at UCLH five months ago. It's secured public funding until March 2010 and if successful, it could roll out across the country. He says it's an idea whose time has come, because it tackles inequality and because the NHS could be directing money to other frontline services.

At UCLH the homeless were attending its emergency services six times more than non-homeless, were admitted four times more often, stayed twice as long, and cost eight times as much. UCLH has practitioners dedicated to caring for the homeless as well as a resident GP, a training scheme, a sanctuary with high-intensity nursing care, as well as a detox/rehab centre to help patients learn the soft skills needed to be rehabilitated into society. As Halligan sees it, if social services, housing and health departments can collaborate, there's no reason it can't work.

Halligan has had a diverse career that has included time as director of clinical governance, and deputy chief medical officer for England. He says his current priority is, "to enable a culture that's patient-centred, safe and high-quality. We need to enable outstanding teamwork, leadership and communication, but above all collaboration. Those aren't skills that are systematically implemented across the service". He reasons: "People's experience of the health service is critical. Standards need to be upheld."

Leadership, he says, is a combination of character and competence. If you don't have boldness, courage and empathy you can't lead. He sees an increasing urgency within the NHS to manage change. "What people recognise is that the solution to enhancing the reputation of the service isn't technical, it's adaptive. You can't command troops into battle, you have to lead them. We're moving from management to leadership."

Halligan is candid about his own leadership: "I know it's been imperfect at every stage. But each time I take a post I'm careful to learn from where I got it wrong. And you know when you've got it wrong. You don't need academic evaluation of the work you're doing. When you get into the zone, and it's resonant with what's good, your leadership style is right."

The biggest lesson he's learned? "Make sure you're aware of those people who resist you. You need to spend more time with those who don't want you to succeed than with your allies".