He was also ordered by the commons to send up Ashburnham, Berkeley, and William Legge as prisoners, and, under protest, obeyed. Thus instead of becoming the king's protector, Hammond found himself his gaoler. His relations with the king were at first pleasant, but after the king's rejection of the 'Four Bills' tendered him by parliament at the end of December 1647, he was more closely confined, and the position of the governor became difficult.
In the king's secret correspondence in the summer of 1648, he wrote of Hammond's incivility. In May 1648 two of the gentlemen attending the king, Osborne and Dowcett, were accused of a plot to abet his escape, and were arrested. Osborne asserted that Hammond's second in command, Major Rolph, had plotted against the king's life, and that the governor was cognizant of it.