The bulk of the collection, some 300 items, comprises correspondence of Rt Hon. Thomas Spring-Rice (1790-1866), 1st Baron Monteagle of Brandon, and his two sons, Stephen (1814-1865) and Charles (1819-1870). His sons served in the Board of Customs and the Foreign Office respectively. The letters are varied in content and, in addition to the information they contain about the family itself, provide many valuable comments on political and economic events at home and abroad, and on the troubles in Ireland in the 1840s. Among the letters is a lengthy epistle from Macaulay to Monteagle, written in August 1834 from India, dealing with party politics and parliamentary affairs.
A further 200 letters were exchanged between Monteagle's grandsons, Cecil and Stephen Spring-Rice, and the latter's wife Julia, 1873-1902.
The collection also contains over 400 letters, papers, newspaper cuttings and photographs relating to Julia's father, Sir Peter Fitzgerald (1808-1880), 19th Knight of Kerry, and fifty letters of his son Sir Maurice (1844-1916), 20th Knight. The material dates mainly from the 1870s and 1880s, when Sir Maurice was equerry to Prince Arthur, Duke of Connaught. Among the correspondents are Prince Arthur, William Gladstone, Arthur Penrhyn Stanley, Dean of Westminster, and Lord Lansdowne. The papers provide useful insights into court and society life, and contemporary political events.
There is also material relating to the Marshall family, to whom the Spring-Rice family were related by Lord Monteagle's second marriage.