From the Wikipedia page 
Letters and Papers of the Reign of Henry VIII, edited by James Gairdner, is a twenty-four volume collection of documents from the reign of Henry VIII of England.
Surviving documents from various archives, the Public Record Office (now The National Archives), and reliable older publications are presented in date order with a volume reference number. The texts are slightly modernised and edited with some explanatory footnotes. Undated documents are printed at the end of the apparent month or year. Grants and payments from accounts are also inserted at the end of their respective months.
The earlier Royal Commission State Papers of Henry VIII, 11 vols, (1830-1852) is not wholly superseded because the editors of that series tried to reproduce the original phrasing and orthography of the selected letters.
Further details can be found here