The Duke of Lancaster's Own Yeomanry (DLOY) was created as successor to older units of yeomanry in the county of Lancashire, and brought together existing troops based in Furness, Bolton and Wigan. The new name was given at an audience granted by William IV to Major Thomas Braddyll in September 1834. The DLOY had continuous existence under this same title until as recently as 1992 when it was reduced in scale to a squadron. The name is now retained by 'D' Squadron (The Duke of Lancaster's Own Yeomanry) as a part of the Royal Mercian and Lancastrian Yeomanry. The unit is thus part of the modern Territorials, but also has a history that encompasses service in the Boer War and World Wars.
The Regimental Collection is an accredited museum with its own trustee body, co-located with the Museum of Lancashire at Stanley Street, Preston. The collaboration with Lancashire County Council Museums Service commenced in the 1980s. The collection includes a small number of paintings and a full range of artefacts telling the history of the Regiment.