This volume has been many years in preparation and accordingly numerous debts of gratitude have been incurred along the way. Three such debts should be warmly and gratefully acknowledged at the outset, for without them this project could not have proceeded. Firstly, the Henry Cromwell correspondence transcribed and annotated here is contained in three volumes of the Lansdowne Collection held by the Department of Manuscripts of the British Library and I am most grateful to the British Library in general, and to the Head of Administration of Western Manuscripts in particular, for granting permission for this material to be published. The correspondence formed the basis of a Master of Letters thesis by Clyve Jones, awarded by the University of Lancaster in 1969 and comprising in large part an annotated transcript of the majority of the letters. Having decided not to prepare a scholarly edition for publication himself, Dr Jones strongly supported my own proposal to work on the material afresh and to prepare an edition for publication. Thus, secondly, I am enormously grateful to Dr Jones not only for his approval and endorsement of my taking on this project – without it, I could not and would not have taken the idea any further, as he had undertaken detailed work on the manuscript well ahead of me – but also for his unfailing help and encouragement throughout its lengthy gestation. Thirdly, I am enormously grateful to a trio of senior academics for the encouragement, help, and support that they offered at the outset, as I framed a formal publication proposal and embarked upon the work: to the late Professor Austin Woolrych, who had himself worked on the correspondence and had supervised Dr Jones's Masters thesis; to Professor Ivan Roots, who supervised my own doctoral thesis on Protectoral central government and who has remained a valued friend and mentor ever since; and to Professor Blair Worden, who was the pre-1700 literary director for the Royal Historical Society at the time that my proposal was submitted and accepted and as serious work began.