Which British physicist confirmed Einstein's general relativity during a solar eclipse?

Arthur Eddington was the British physicist who helped confirm Einstein’s general relativity during the solar eclipse of May 29, 1919. He led one of two British-led expeditions that tested the theory’s prediction that gravity bends starlight.

Eddington travelled to Príncipe, an island off the west coast of Africa, while another team observed the eclipse at Sobral in Brazil. During totality, the teams photographed stars near the Sun. Comparing their apparent positions with measurements made when the Sun was elsewhere showed whether the Sun’s gravity shifted the starlight.

General relativity predicted roughly twice the light deflection expected from a Newtonian calculation. The results were announced at a joint meeting of the Royal Society and Royal Astronomical Society in London in November 1919, helping make Einstein internationally famous.

Eddington was not the only person involved: Astronomer Royal Frank Dyson organized the broader test, and observers in Brazil made crucial measurements. Still, Eddington is the canonical answer because he directed the Príncipe expedition, understood the theory deeply and presented the findings.