She settled at the age of 50 at Rise Cottage on the Cashmere Hills near Christchurch, with her companion Effie Pollen, where she created a sheltered garden with views over the city and towards the Southern Alps, and began writing poems about the landscape.

[5] Having enough private wealth to support herself, she took up social work in London with the Anglican organisation Women Workers for God, or "Grey Ladies".

[2][9] The theory that Bethell's relationship with Pollen was homosexual (which would have sat ill with her Anglicanism and her social aspirations in that period) was explored in some detail by the fellow poet Janet Charman, as a visiting scholar at the University of Auckland in 1997.

[2] She was deeply affected by Pollen's death in 1934, writing to a friend that the event was "a complete shattering of my life.... [for] from her I have had love, tenderness, and understanding... and close and happy companionship".

[8] Her poetry is ascribed by the Oxford Companion to Twentieth-Century Literature in English "a plainness and spareness (as well as freshness of image) which distinguishes it from the more ornamented verse the country had previously produced.

"[11] The New Zealand writer Charles Brasch, visiting Bethell in the late 1930s, found her at "the centre of an astonishingly diverse circle of interesting people, many of the younger of whom were so close to her that she almost directed their lives.

The educator and writer Crawford Somerset opined, "New Zealand has produced no other poetry so clearly original and so delicately sensitive as Ursula Bethell's.

"[14]: 281  The poet and journalist D'Arcy Cresswell said that in literature "New Zealand wasn't truly discovered, in fact, until Ursula Bethell, 'very earnestly digging', raised her head to look at the mountains.

In 2021, these archival papers were inscribed on the UNESCO Memory of the World Aotearoa New Zealand Ngā Mahara o te Ao register.