The archive comprises mainly correspondence addressed to Sir Walter and his first wife Pauline Lady Trevelyan nee Paulina Jermyn. The letters reflect the couple's interests in natural history, botany, geology, antiquities, travel, temperance, phrenology, art and literature, and include examples from many well known contemporaries.

There is also material relating to the history of the Trevelyan family, accumulated during Walter and Charles Edward Trevelyan's preparation of 'The Trevelyan Papers' for publication.

The archive also features diaries and journals, sketchbooks, notes for speeches and scrapbooks. There is material relating to the North East of England, including proposed railways, Tyne crossings at Hexham and decoration of the Great Hall at Wallington.

The diaries of Thomas Sopwith (1803-1879), mining engineer, land surveyor and philanthropist in the north-east of England, cover the period 1828-1879. We hold both the original diaries, and a copy of the material held on 16 reels of microfilm. They form a meticulous account of the professional life of Sopwith, detailing his work, projects and his travels both for business and for enjoyment. The diaries also include sketches and illustrations of people, views, and buildings and often include descriptions of lectures and conversations with people Sopwith met on his travels.A particularly notable aspect of the diaries is Sopwith's descriptions of journeys he made by rail, often along newly-opened railway lines in a period where rail travel was in its early stages.

This is a small collection of notebooks and photograph albums which belonged to John William Heslop Harrison (1881-1967), at one time Professor of Botany at Newcastle University. The notebooks contain notes on plant biology, pollination and plant genetics while the albums include photographs of Iraq, dated 1938-1941. The collection also includes Proceedings of the University of Durham Philosophical Society 1955-1956 in various stages of editing.

The papers and photographs of Gertrude Bell mainly consist of the letters Gertrude Bell sent home to her family whilst on her travels, of the diaries she kept when abroad, and the photographs taken whilst she was away.

The papers consists of sixteen thousand letters, sixteen diaries, seven notebooks and forty-four packets of miscellaneous material; whilst the photographic collection is about 7000 in number, and consists of photographs taken by her between c.1900-1918. Those of Middle Eastern archaeological sites are of great value because they record structures which have since been eroded or, in some cases, have disappeared altogether, while those of the desert tribes are of considerable anthropological and ethnographical interest.

Her competence as a field archaeologist and photographer means that the papers are indispensable for archaeological research of parts of the Middle East.

The items in the Bell Miscellaneous Papers contain material relating to Bell's work and travels, including contemporary articles, notes by Bell on various topics (archaeological sites, Arab tribes, etc.), letters concerning the publication of Bell's letters by Lady Richmond and letters to and from Gertrude Bell, maps and plans, literary manuscripts, lecture notes and copies of letters from Gertrude Bell held elsewhere. There is also a series of the letters known as the Doughty-Wylie letters, 1913-1915. These are the letters between Gertrude Bell and Charles Doughty-Wylie, an army officer with whom Bell was in love. The letters were returned to Gertrude Bell after his death at Gallipoli in 1915.