The fine art collection is a result of many bequests, donations and purchases since 1927 and contains almost 6000 easel paintings, works on paper and miniatures.
The greater part of the collection consists of British paintings, drawings and prints from the 19th and 20th centuries, representing the traditions of topography, landscape, portraiture and still-life, complemented by a small collection of works from the 16th to 18th centuries. Contemporary art is also actively collected. There are works by George Stubbs, J.M.W. Turner, Mierevelt, L.S. Lowry, Henry Moore, Terry Frost, and the splendid portrait of Joseph Banks by Benjamin West. Lincolnshire born artists and those associated with the county are well represented, including William Logsdail, William Warrener, C.H. Shannon, Peter DeWint and Karl Wood.
The collection of miniatures, part of the James Ward Usher bequest, from the 17th to the 19th centuries, features portraits of the English and French royal families, the nobility and various distinguished personalities.