It is a pleasure to acknowledge those whose expertise, friendship, and support I have valued in preparing this edition. I undertook the task of transcription partly during the Covid lockdown of 2020. Skilled Latinists – John Bergin, John Minahane, Claude Pavur SJ, and Patrick Sammon – provided English translations of these texts. A further revision ensued; the editor takes responsibility for the translations presented here. Regarding the Italian items, my transcriptions and translations have benefitted from Diego Zancani’s expert observations. Maurice Whitehead, archivist of the Venerable English College, Rome, has been unfailingly supportive and generous, not least in clarifying elements of the College’s internal organization in the early modern era. At the Bibliothèque royale de Belgique/Koninklijke Bibliotheek van Belgie (KBR) in Brussels, the codex containing the Slingsby materials was professionally restored in 2020, thus facilitating a fuller and more accurate transcription; I am grateful to Sara Lammens, director, and Tatiana Gersten, conservator, for this comprehensive intervention. At the Royal Historical Society, Andrew Spicer and Siobhan Talbott accompanied the proposal at various stages; I am grateful to Jem Langworthy at Cambridge University Press for the diligent copy-editing.

I appreciate the encouragement and guidance of colleagues at Archivum Romanum Societatis Iesu, Rome (ARSI), where this project began. I join the long list of researchers in Jesuit history who have benefitted from the prompt and professional responses of Mauro Brunello to various queries. Work on the edition was greatly facilitated by the volume superbly edited by Vera Moynes, The Jesuit Irish Mission: A Calendar of Correspondence 1566–1752, and expertly published by Institutum Historicum Societatis Iesu (at ARSI), in 2017. In Brussels, I have valued the hospitality of the Jesuit community at St Michel while on visits to the KBR. Campion Hall at Oxford has been a supportive academic community within which to complete this project, and I thank the Master, Nicholas Austin SJ. At Campion, the generous interest of Peter Davidson and the professional assistance of then librarian Wilma Minty have eased the burden of research. On various visits to Dublin, the Jesuit community at Leeson St has always been welcoming. Successive Irish Jesuit provincials Leonard Moloney and Shane Daly have supported this and other endeavours in Jesuit history.

With enthusiasm and expertise, Alan Ford has commented on earlier drafts of the Introduction. In identifying various English Jesuits, this edition has benefitted from the published work of Thomas McCoog SJ, who in addition has kindly read the Introduction, as did Declan Mac Cuarta, with his customary attention and interest. Style and content have improved thanks to the readers’ diligence and skill. I am grateful to Matthew Stout for preparing the maps.

The following freely shared their knowledge of the sources, and helped clarify various points: Ian Campbell, Bernadette Cunningham, Kathleen Duchatelet, Carter Fahey, Jan Grayfius, Clare Hopkins, Gasper Jakovac, Bernard Joassart SJ, Gerard Kilroy, Cynthia Liu, Carlo Luongo, John McCafferty, Brid McGrath (1958–2025), Thomas O’Connor, Brian O’Leary SJ, Bart Op de Beeck, Therese Osborne, Ruth Selman, Rebecca Somerset, and Jane Stevenson.

I thank the staffs of the various institutions in which relevant material was found: Archive of the Congregation for Doctrine and Faith, Rome; ARSI; Archives of the Venerable English College, Rome; Biblioteca Apostolica Vaticana; KBR; The National Archives, London; Société des Bollandistes, Brussels; Stonyhurst College Archives; and Trinity College, Oxford.

Since first encountering him at an Irish History Students’ Association meeting in June 1975, Raymond Gillespie (1955–2024) has been a lifelong friend and generous mentor in the study of early modern Ireland; his erudition, sound advice, and infectious enthusiasm have been a constant source of encouragement, and inspiration. Requiem æternam dona ei, Domine: et lux perpetua luceat ei.