In later life, while living in London, George Claessen returned to poetry, often interrogating the same metaphysical themes he explored in his abstracts. The fruits of these endeavours resulted in a number of volumes, including, Poems of a Painter published in 1967, Poems about Nothing (1981), Collected Poems, (1995) and subsequent inclusion in various poetry anthologies.

Describing his desire to use poetry as a creative alternative to his visual artistic work, he memorably said that it was, '...the outcome of an urge for expression in another form - a phenomenon not uncommon in painters, just as the same would and does apply in reverse to essential poets'.