From a small office in a leafy corner of south London, a small team of British researchers are directing one of the most dangerous rescue missions on earth.

Their work, unfolding far from the quiet streets of New Malden, supports a journey menaced by risk that begins with a dash across the border of North Korea.

The Korea Future Initiative has become the first British organisation working to directly save fugitives from the world’s most oppressive regime.

For around £1,700, it is claimed, a North Korean can be evacuated from the parlous hinterlands north of the border to a place promising freedom from tyranny, South Korea.

The money is used to transport refugees along a subterranean route from…