The children, aged between 10 and 14, were walking the ancient pilgrims trail from Canterbury to London to highlight their petition for urgent government action to help prevent damaging climate change. Dr Williams, who signed the petition, welcomed the group to Lambeth Palace, where they received a tour of the building and enjoyed a question and answer session, before leaving to meet their MP and present the petition at 10 Downing Street.

The children, who were accompanied on the walk by teachers and parents, had designed their own t-shirts to spell out their slogan 'ECO-MAD' (Every Child's Opportunity to Make A Difference). After Dr Williams had thanked the party for their dedication and spirit, the children gave him some poems and artwork that they had created with an environmental theme.

Claire Foster and David Shreeve, who manage environmental policy for the Church of England's Mission and Public Affairs department, were also on hand to answer questions about the work the Church of England is engaged in to combat climate change. They shared with the children details of the CofE's 'Shrinking the Footprint' campaign, which involves an audit and eventual reduction of the carbon footprint of all Church of England buildings.

Dr Williams said:

"The children of Exeter Cathedral School should be rightly proud of what is a great achievement. They have taken on this huge task with immense determination, focus and spirit. We must act now, and act together, if we are to prevent permanent and irreversible damage being done to the planet. The prayers and concerns for safe stewardship of God's Creation shown by these children sets a marvellous example for us all."