Complex sentence: In 1943 she was awarded a diploma in drawing and painting by the Glasgow School of Art. Her diploma painting, a self-portrait, was her only excursion into formal portraiture and she was awarded the school's Sir James Guthrie Prize for it.
Split into simpler sentences: In 1943 she was awarded a diploma in drawing and painting, and won the Sir James Guthrie Prize for portraiture. Eardley's 1943 "Self-portrait" was her diploma self-portrait at the Glasgow School of Art. It was her only excursion into formal portraiture and she was awarded the school's Sir James Guthrie Prize for it.