During the turbulent years of the Civil War and the Protectorate of Oliver Cromwell Thomason reputedly moved the collection several times to protect the more controversial works from destruction by government or opposition censors.
[2] Thomason appears to have entrusted the collection to the care of Thomas Barlow, provost of The Queen's College and former librarian of the Bodleian Library at the University of Oxford, and a future Bishop of Lincoln.
Thomason remained hopeful that they would be sold, and in his will dated 1664, he charged his three executors (Barlow, Thomas Lockey, and John Rushworth) with selling the collection to the University on behalf of his children.
After Thomason's death in April 1666, the negotiations fell through and the collection remained in Barlow's hands, until they were acquired about 1677–1679 by the bookbinder Samuel Mearne on behalf of the Royal Library at the Palace of Whitehall.
Over the next four decades various members of the Sisson family (descendants of Samuel Mearne) endeavoured to sell the collection on numerous occasions to Robert Harley, 1st Earl of Oxford and Earl Mortimer, the Bodleian Library, Thomas Thynne, 1st Viscount Weymouth, James Brydges, 1st Duke of Chandos, Frederick, Prince of Wales, the Radcliffe Library in Oxford and the antiquary and book collector "Honest Tom" Martin, but in each case the potential purchasers were put off by the high price asked.