The University of Utah singers joined worshippers at St Mary's, Thame for a Daybreak service in July.
The choir is currently on its European tour and called into Thame on their way to a day's sight-seeing in Oxford.
Organist Graham Choldcroft said: 'People left worship feeling extremely uplifted by their contribution. And the choir were thrilled to be in such an ancient building.
'50 years is old where we come from!' said one.
