Margaret Emma Faith Irwin was born at Highgate in London. Following the deaths of her parents in childhood, she was raised by a paternal uncle, a classical scholar. She attended the Clifton School in Bristol and then Oxford University. In 1929, she married John Robert Monsell, an artist and illustrator of children’s books. Margaret Irwin began publishing stories in 1924, and was awarded first prize in the Historical Novel Competition organized by the London publishers Chatto and Windus for her story None So Pretty in 1930. She went on to establish herself as a successful historical novelist, recognized by readers and critics for her considerable talent. The dustjackets of her books were designed by her husband. Margaret Irwin was a friend of the history scholar and writer Dame Cicely Veronica (C.V.) Wedgwood.