Valerie Shepard and Steve Saint, Mike Lanchin’s guests in Witness (23 February) – part of a week’s worth of outings on Radio 4 for the World Service staple – shared a deeply un-enviable distinction. Back in January 1956 their fathers, Jim Elliot and Nate Saint, were hacked to death by the members of a tribe of Amazonian Indians whom they had been attempting to convert to Christianity.

The trail led back to a post-Second World War Ecuador at a moment when change was in the air. Railway lines were connecting major cities to the Pacific. Mining corporations were at work in the rainforests. With them came American missionaries, who established their families in communal houses on the forests’ edge and then flew over the treetops in light aircraft looking for evidence of human settlement.