What is the background and publication information for "I Think Continually of Those Who Were Truly Great"?

Stephen Spender (1909 – 1995) was an English poet, essayist, translator, and literary critic, who traveled widely, living in the United States and Europe as well as Britain. He was a member of Auden's circle and was acquainted with and wrote about many of the leading figures of his period. “The Truly Great”, which is the actual title of this work, was published in Spender's Collected Poems 1928-1953 in 1955.