Beckman returned to London to report to Lord Arlington, who had been warned that 'Beckman the Intelligencer is to be feared' and made the mistake of visiting the Dutch ambassador (Marshall, 180). He was arrested and until early 1664 was held in the Tower, from where he complained 'I have been near a half year a close prisoner only from one persons malicious and false tongue' (TNA: PRO, SP 29/89, fol. 6).