Collected Poems covers some thirty years from 1972 until 2001. His individual collections have usually taken as their subject one predominant theme - the enigmas of prehistory, his wartime childhood, the passing of the Edwardian generation his parents belonged to. He has always been particularly concerned with the formal and patterned use of language, and would like to think that his poems exemplify Auden's belief that poetry is 'a game of knowledge'.