A major theme in the work of Michael Prestwich, as in that of his father, J. O. Prestwich, has been the importance of the king's household knights. In his first book, War, Politics and Finance under Edward I, published in 1972, Michael asked and answered such key questions as ‘how were [knights] recruited for the household, how long did they serve, and what were their rewards?’ He showed that the knights, a body about 100 strong in 1284–5, formed the core of royal armies, and ‘might also be used on matters of state quite unconnected with the business of campaigning’. Thus they, or at least the most senior amongst them, acted at court as counsellors, abroad as diplomats, in parliament as members of the peerage, and in the localities as keepers of vacant bishoprics, commissioners of array, and enforcers of law and order. The household knights were central to Edwardian rule.

Since Prestwich wrote in the 1970s, the thirteenth-century household knights have been studied by such scholars as Ruth Ingamells, Kenneth Lightfoot, Beth Hartland and Stephen Church. Church's book, the first devoted exclusively to the household knights of any reign, showed how many knights King John had, and how he recruited, used and rewarded them. They were just as essential to the maintenance of his rule as were the knights later in the century to the rule of Edward I or indeed the knights 100 years before to that of Henry I, the latter the subject of an influential article by J. O. Prestwich.