He ever opposed Cromwell's usurpation with zeal and courage; and after making all efforts against the restoration, he resolved to take no benefit of the general indemnity, but chose voluntary banishment, rather than submit to a government and family which he abhorred.

As long as the republican party had any existence, he was active in every scheme, however unpromising, which tended to promote their cause; but at length, in 1677, finding it necessary for his private affairs to return to England, he had applied for the king's pardon, and had obtained it.

When the factions arising from the Popish plot began to run high, Sidney, full of those ideas of liberty which he had imbibed from the great examples of antiquity, joined the popular party; and was even willing to seek a second time, through all the horrors of civil war, for his adored republic.
From this imperfect sketch of the character and conduct of this singular personage, it may easily be conceived how obnoxious he was become to the court and ministry: what alone renders them blamable was, the illegal method which they took for effecting their purpose against him.

On Sidney's trial, they produced a great number of witnesses, who proved the reality of a plot in general; and when the prisoner exclaimed, that all these evidences said nothing of him, he was answered, that this method of proceeding, however irregular, had been practised in the prosecutions of the Popish conspirators; a topic more fit to condemn one party than to justify the other.

The only witness who deposed against Sidney was Lord Howard; but as the law required two witnesses, a strange expedient was fallen on to supply this deficiency.