Some more information about the artist Helen Rohan from the Unicover website:
Helen Rohan Australian
Helen Rohan was born in Sydney, Australia, and raised in Canberra, Australian Capital Territory, where she developed a keen interest in art. She received a graphic design degree in 1978, and while at college she became intrigued with illustration. After graduating, she worked for two advertising agencies in Melbourne, which helped her gain experience and furthered her interest in illustration. Rohan has worked on many stamp projects for the Australian Post where she has had the chance to cast stamps for countries around the world. Designs Rohan has been involved with include the Australia Boy Scout Jamboree stamp, the First Day Cover for Australia Day 1980 and the Cover for the October issue of the Australian Stamp Bulletin.