Bastard Feudalism is one of the most significant concepts to analyse the socio-political and economic relations in late medieval English society. This term was invented and developed by the nineteenth century English historians such as Charles Plummer and William Stubbs with negative connotations to explain the late medieval political and socio-economic order. For these historians, Bastard Feudalism signified a change from fief-centred classic feudalism based upon contract between lord and vassal into a cash-based retaining system. Beginning from the reign of Edward III, the English kings allowed great lords of the realm to make contracts with those from lower sections of the society to finance military campaigns. This new system based upon cash payments enabled the lords to create new dependency service outside the control of the central government. Therefore, it has been regarded by the historians as a demonstration of degeneration in the social structure. In the twentieth century, K.B. McFarlane criticised the conventional approach to the concept of Bastard Feudalism. He revaluated the concept and claimed that Bastard Feudalism could be considered as a process of adaptation of the kings and their subjects to the new conditions. The historians still debate whether Bastard Feudalism was the source of political conflict and social turmoil. This article evaluates the historiographical debates on Bastard Feudal system and emphasizes that it was a necessity for proper operation of late medieval English society since the kings needed the aid of great lords in the governance of the localities.