Justin started his career with Oxfam as a Policy Adviser on South Africa during the dying days of apartheid, a cause which had been close to his heart as an activist. At Oxfam he rose through the ranks and helped build campaigns on debt cancellation, Africa, Make Trade Fair and access to medicines. In 1995 Justin went out to Washington DC to set up Oxfam International, before returning in 1999 as Policy and Campaigns Director. He helped build Oxfam as a global campaigning force. In 2004, Justin was recruited to Number 10 by Tony Blair where he led efforts on poverty and climate change and was one of the driving forces behind the Make Poverty History campaign. He was to stay on under Gordon Brown, becoming his Strategic Communications and Campaigns Director, helping to use new communications strategies to reach the British public on a range of issues from knife crime to climate change. Justin was appointed as Chief Executive of Save the Children in September 2010.
As Chief Executive, Justin has increased the charity’s impact for children, increasing its income in the past 5 years by over £150m, recruiting hundreds of thousands of new supporters, pioneering new innovative strategies for change from the humanitarian leadership academy to the No Child Born to Die campaign - enabling it to more than double the number of children it reaches from 8m to 17.4m in recent years.