Born at Lamorna, the second daughter of Samuel John Lamorna BIRCH and Houghton VIVIAN, Joan also appears with Mornie as a model child in paintings by the Newlyn artists. She herself painted landscapes and coastal scenes in oil and watercolour, and married John Paxton-Petty in 1934, the same year in which she submitted a painting to the RA, which was accepted.

Her earlier years were spent in Lamorna, where she worked together with her mother and sister on crafts and toys that they sold in the summer months at the 'shop' at the bottom of their driveway. She emigrated to Australia with her husband in 1946, and was visited by her father in his Australasian travels. She died there, three years after her sister's death in Lamorna.