Inside the back rooms of the British Museum in London, Rodney Kelly felt the weight of his people's history as he picked up a sacred shield once held by his ancestors.

It was a bittersweet moment for Mr Kelly, who would dearly like the wooden shield to come home.

"It was really emotional," he told the ABC.

"But that proud moment and happy moment just turned to sadness and sorrow because I knew the shield was going back into its case."

Encased behind glass in the British Museum, the 'Gweagal Shield' is a priceless artefact that many believe tells the story of Captain James Cook's arrival in Australia, and the resistance of Aboriginal tribes on the frontier.

Mr Kelly said the shield was owned by his ancestor Cooman, who confronted Cook during his first encounter with Aboriginal people at Botany Bay.

The Gweagal Shield sits encased behind glass at the British Museum. ( ABC News: :Lincoln Rothall )

With a pierced hole near the centre of the shield, the museum states that it "has been suggested but not confirmed" that this is the shield held by Cooman when he was shot at by Cook's landing party.

Mr Kelly was invited to inspect the artefact at the museum in London this month — a significant step in his long-running campaign to have the shield returned.

Rodney Kelly smiles while holding the Gweagal shield. ( Supplied: Rodney Kelly )

Mr Kelly, a Dharawal and Yuin man from the south coast of New South Wales, has travelled to London several times in the past four years, pressing the museum to repatriate the "stolen" shield.

"They can see that I'm not going to quit, I think that was the best thing they could do was to pull the shield out from the case and let me hold it," he said.

"I'm just going to keep coming."

A 'museum of the world'

The British Museum is one of the key institutions at the centre of a debate in Europe over the repatriation of remains and sacred artefacts taken without permission from their countries of origin.

The museum is prevented by law from returning antiquities and artworks, spokeswoman Hannah Boulton said.

But as one of the UK's largest attractions, the British Museum also sees itself as a "museum of the world, for the world", with millions of objects held in its vast collection.

"The museum's position has always been clear: we feel that the benefit of the collection like the museum's is its strength and breadth, we are here to represent all cultures," Ms Boulton said.

Hannah Boulton is the Head of Press and Marketing at the British Museum. ( ABC News: Lincoln Rothall )

"We want to make sure we retain the collection as an entity.

"Having said that, we're always happy to think about ways we can share the collection more widely, through loans or through working together to collaborate to understand and interpret the collections better."

Mr Kelly, though, doesn't want the shield sent on loan — it was last sent to Australia for the National Museum of Australia's Encounters exhibition.

His vision is for it to be repatriated and displayed at Kurnell, south of Sydney, Cook's first landing place.

"Back home there's a real need for true history to be told," he said.

"The significance to our culture far outweighs any visitors who come here and just stroll past the shield without really knowing the history of it."

The push for 'decolonisation'

Last month, Greek President Prokopis Pavlopoulos called on the UK to return the Parthenon marbles from the "murky prison" of the British Museum, and hundreds of protestors have demonstrated inside the British Museum this year, calling for the return of items to Greece, Iraq, the Palestinian Territories and Australia.

Sculpture of Greek river god Ilissos, part of a collection of stone objects, inscriptions and sculptures known as the Elgin Marbles, on show at the Parthenon Marbles' hall at the British Museum. ( Reuters: Dylan Martinez )

"We see ourselves as a place for debate, we obviously have collections that inspire a lot of discussion," Ms Boulton said.

"We've always been very clear that anyone can come to the museum and make their voices heard and see the objects."

Dr Chris Garrard, co-director of Culture Unstained, said there was a "growing conversation about decolonisation" in the UK.

Dr Chris Garrard is the co-director of Culture Unstained. ( ABC News: Lincoln Rothall )

"We're kind of moving away from this idea that large museums, like the ones we see in London, are neutral spaces — they're not."

Mr Kelly said his journey had been "a struggle".

"It's been so hard, and hard for my family back home … but it's not about me, it's about my people back home, and other Indigenous people around the world," he said

"I have to put my hardships aside to make sure repatriations are more talked about."