Additional material from the reigns of Edward VI, Mary I, Elizabeth I and James I, not known when SP 10-SP 14 were created, assembled both from different series of records kept by the State Paper Office itself including Border Papers and Channel Island Papers, and from entirely separate collections not previously connected to the State Paper Office. The series was formed
Most of the disparate material was sorted and bound up in volume form between the 1850s and the 1870s, except for five original items within the series which remained separate. The Border Papers include correspondence of both the Council of the North and the Wardens of the Marches (with both the Scottish and English courts) and so include papers relating to the Northern Rebellion of 1569-1570.
Other documents in the series are unofficial papers addressed to residents abroad, containing domestic information, and similar papers, written from abroad, by travellers or English Catholic fugitives living in France and the Low Countries.
In addition, the series includes papers redated from the earlier chronological arrangement for SP 10 - SP 14, following further investigation, certain papers from 'Exchequer sacks', and documents removed from the Conway Papers including a collection of holograph letters from Robert Dudley, Earl of Leicester, to Elizabeth I. The former Conway Papers for the reign of James I now in this series fill many gaps in the State Paper Office's records.