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.

Manuscript transcripts of radio communications created by members of the British North Greenland Expedition (BNGE) while in Greenland. The messages cover communication between individual expedition members, units of the expedition, and external parties such as American and Danish military bases and the expedition's main external point of contact and control which was referred to as Pakice and located in London.

The expedition took place over two phases between 1952 and 1954 and undertook a range of work on the North Greenland Icecap including glaciology, seismology, geology, gravitometry, radio wave observations, and mapping of the ice sheet. The expedition also provided an important test bed for British polar research capabilities more broadly, including logistics, communication and medicine. Members of the expedition team were predominantly members of the military, but it included several members who would later have notable careers in academia and research, including Hal Lister, James Simpson, Stan Paterson and Peter Wyllie.

The communication include reports of progress and scientific measurements, discussions regarding expedition plans, records of incidents and their resolution, and communications between expedition members and family.

Transcripts cover most of the period of the expedition, and include messages sent and received. However, the archive is not a full and complete set of transcripts. There are no transcripts in the archive covering the first 2 months of the expedition, nor for between January and April 1953.