It had been a thousand miles of blisters, rain and toil. But there were smiles on the faces of the 18 Cut the Carbon marchers as they walked the final few metres of their journey down the aisle of St Paul's Cathedral.
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The campaigners, who had started their long journey in Belfast on 14 July, received a standing ovation from the hundreds of people who had turned up for a service of thanksgiving for their efforts.
In an opening prayer, Christian Aid director Dr Daleep Mukarji thanked the walkers for their commitment.
'Following their example,' he said, adding that we should 'redouble our efforts to make the suffering of the world's poorest people more widely known and do whatever we can to bring about a swift reduction in carbon emissions.'
A view from Congo
The impact of climate change on the world's poorest communities was then highlighted in an interview with one of the walkers - Chirhalwirwa Murhambo from the Democratic Republic of Congo.
The emergency officer for Christian Aid in Bukavu - a region of the Congo known more for its border wars than climate change - had decided to join the march after witnessing the destructive force this year of the African rains.
'Millions of people across Africa have been displaced by this year's floods,' Chirhalwirwa told the congregation. The people who have had no responsibility for climate change are those who are most affected by it, he added.
‘We are no longer free to do as we wish’
In a sermon, the Right Reverend John Gladwin, Bishop of Chelmsford, said that people were now waking up to the impact of their carbon footprint on the world's most vulnerable people.
The realisation was growing, he said, that we are 'no longer free to do as we wish', because that freedom 'deepens the poverty of others.'
It was a time to develop a vision on how to tackle our carbon emissions, Bishop Gladwin, who is also the chair of Christian Aid, added. In that respect, the marchers had shown us the way.
'Why would you spend 80 days walking across these isles unless there was a vision,' he said.
That vision, that commitment, earned the marchers another standing ovation as the service drew to a close.