[1] McCullough's poetry uses surreal imagery to explore themes including sexuality, the body, history, mental health and class.
[2] He is influenced by writers including Frank O'Hara, Elizabeth Bishop, Anne Carson, John Ashbery, Lee Harwood and Rosemary Tonks.
[4][5] In 2016 Penned In The Margins published Spacecraft, a collection focussed on the idea of absence and emptiness as forces with creative effects.
[6] [7][8] Penned In The Margins went on to publish Reckless Paper Birds in 2019, a collection which explores the vulnerability of the body, especially as it relates to queer identity and politics.
Its poems include the long, Forward-shortlisted piece 'Flower of Sulphur', which draws on McCullough's Ph.D research into rhetoric and friendship in Renaissance England.