In 1974 with the encouragement of Professor Elton, I began to prepare a new calendar of the State Papers, Domestic for the reign of Edward VI. These papers, which constitute the kernel of the surviving archive of the principal secretaries, were among the first Record Office papers to be described in print; but the calendar edited by Robert Lemon in 1856 and which covered the years 1547 to 1580 offered only very brief treatment of the contents of the eighteen volumes of letters and papers which make up the domestic series for Edward's reign: manuscripts were generally identified in a few lines of description often taken verbatim from the endorsement of the originals. It was soon recognised that such a modest method was inadequate, and subsequent volumes have presented more extended summaries. One consequence of the comparatively meagre calendaring of the SP 10 series has been that the original manuscripts have been much more frequently consulted than would otherwise have been necessary, with the inevitable result that their physical condition has seriously deteriorated; this was a major consideration in commissioning a new and comprehensive calendar to replace Lemon's early work. Although it was decided not to incorporate any material not included in the original calendar, the opportunity has been taken to reflect modern evaluation of the dating and authorship of some of the manuscripts – the unsurprising consequence of more than a century of research since the first calendar was published. Some papers have indeed proved not to belong to the reign of Edward VI at all.