The Prime Minister is due to arrive in Samoa when the clock strikes midnight on Thursday UK time for the Commonwealth Heads of Government Meeting (Chogm).
His arrival comes amid a row over reparations for the UK’s historic role in the transatlantic slave trade, but Sir Keir insisted the Commonwealth must look forward, not back.
Sir Keir will make history as the first UK prime minister to visit a Pacific island nation and will be in the company of King Charles, the head of the British Commonwealth, during the meeting.
The prime minister is expected to make the case for strong economic bonds across the association, including by setting up a new UK trade think tank, run by the Foreign Office.
While the Commonwealth includes the UK’s established trading partners such as Canada, Singapore and Australia, the Prime Minister is also looking at opportunities with developing member states.
This includes six of the world’s 10 fastest growing economies: Guyana, Rwanda, Bangladesh, Uganda, India and Mozambique.
At Chogm, he will also meet business leaders from Bank of America and Lloyd’s of London following the recent investment summit he hosted in London.
“We have a once-in-a-generation opportunity to fix the foundations to turn around the lives of ordinary people in the UK, but we can’t do that with a protectionist approach,” the Prime Minister said.
He added: “In line with this Government’s pragmatic and sensible approach, we must seize opportunities to work with real partners – like our Commonwealth family – around the world to build sustainable economies that offer real opportunities for our people, regardless of whether it is access to untapped markets or collaboration in mass innovation.
“With the Commonwealth’s total GDP expected to exceed $19.5 trillion over the next three years, we cannot let this economic weight go to waste.”
As he traveled to the summit, Sir Keir insisted that calls for reparations for slavery were not on his agenda.
“On the question of where we are facing, I think we should be facing forward,” he told reporters.
“I have spoken to many of our Commonwealth colleagues in the Commonwealth family and they are facing real challenges in terms of things like climate in the here and now.”
Sir Keir said other nations in the association were more interested in raising money to tackle the effects of climate change
“That’s where I’m going to put my focus, not what will end up being very, very long endless discussions about reparations for the past,” he added.
The Prime Minister said there was “no doubt” that slavery was “abhorrent”, adding: “But I think from my point of view, and taking the approach I have just taken, I would prefer to roll up my sleeves and work with them on current challenges focused on the future rather than spending a lot of time on the past. That’s my focus.”
The political leaders of India and South Africa – Narendra Modi and Cyril Ramaphosa – both snubbed Chogma to join the BRICS summit in Kazan, Russia, alongside Vladimir Putin.
Sir Keir said it was “their question where they attend” when asked for their views on their decision to prioritize the BRICS meeting.