She has published six books of poetry in Welsh and English. Her first collection in English, Parables & Faxes (Bloodaxe, 1995) won the Aldeburgh Poetry Festival Prize and was short listed for the Forward, as was her second, Zero Gravity (Bloodaxe, 1998). The BBC made a documentary of Zero Gravity, inspired by her astronaut cousin's voyage to repair the Hubble Space Telescope. Y Llofrudd Iaith ('The Language Murderer', Barddas, 2000), won the Welsh Arts Council Book of the Year Prize and Keeping Mum was short listed for the same prize in 2004. She composed the words in six-foot high letters on the front of Cardiff's iconic Wales Millennium Centre. She is one of the poets in the Poetry Book Society's Next Generation promotion and was recently given a major Creative Wales Award.

Gwyneth's first non-fiction book, Sunbathing in the Rain: A Cheerful Book on Depression (Flamingo 2002), was shortlisted for the Mind Book of the Year and was recently broadcast as a play on BBC Radio 4. Her second, Two in a Boat: A Marital Voyage, recounts a voyage which she made with her husband from Cardiff to North Africa. She has written three libretti for Welsh National Opera. The first, The Most Beautiful Man from the Sea to music by Richard Chew and Orlando Gough was performed by a choir of five hundred. Redflight/ Barcud, music by Richard Chew and Dolffin, music by Julian Philips, have toured schools in Wales and England. She was Poet in Residence at the Physics and Astronomy department of Cardiff University in 2005.

Gwyneth was a scholar at Girton College, Cambridge and was awarded a double first in English literature and the Laurie Hart Prize for outstanding intellectual work. She received a D.Phil in English from Oxford, having written a thesis on eighteenth-century literary forgery. She is a Fellow of the Royal Society of Literature, a member of the Welsh Academi and a NESTA Fellow. NESTA is the National Endowment for Science, Technology and the Arts, the organisation that invests in UK creativity and innovation. In 2005 she was elected Honorary Fellow of Cardiff University. In the past she spent three years in the US as a Harkness Fellow and was a documentary producer and director at BBC Wales, where she won a BAFTA. She left the BBC to become a freelance writer.