This series consists of nine notebooks containing draft poems, covering the period 1897-1957, and thirty additional enclosures (now housed in separate envelopes). Many of the notebooks contain both poetry and additional material such as diary entries, prose drafts and notes. Sassoon frequently used the notebooks in both directions, writing poetry from one end, and rotating the notebook to write notes, prose or diary entries in the other.

The earliest notebook in the series, MS Add. 9852/6/1, is an illustrated book of poems written by Sassoon when aged ten, compiled as a birthday gift for his mother. Two notebooks date from the Great War period: MS Add. 9852/6/2 which contains fair copies and corrected drafts of poems dated 1916-1918, neatly transcribed by Sassoon, and MS Add. 9852/6/3 which contains draft poems and diary entries dated 1917-1918. Some poems in these and other notebooks show evidence of significant revisions before their final publication. An early draft of 'The Dug-Out' in MS Add. 9852/6/2, for example, ends with four additional lines not found in the published version. The remaining notebooks contain later poetry, dating from c.1920-1957. MS Add. 9852/6/4 contains poems from 1931-1939 along with autobiographical notes on Gosse, Hodgson, and Hardy. MS Add. 9852/6/5 contains poems dated 1924-1930, many of which were published in 'The Heart's Journey'. MS Add. 9852/6/6 contains poems dated 1933-1939 and includes watercolour illustrations. MS Add. 9852/6/7 includes poems dated 1947-1950 and some earlier works, along with notes for 'Meredith' and text on Wilfred Owen and Charlotte Mew. MS Add. 9852/6/8 contains poems dated 1947-1955, many of which were intended for publication in 'The Tasking'. MS Add. 9852/6/9 contains poems dated 1951-1957 and further 'Meredith' notes.

The notebooks are arranged chronologically, with poems listed by title where provided; for untitled poems the first line is given.