But, though a Spanish invasion of England to restore the Stuarts was his great game, an assassination of Cromwell anyhow, whether without a Spanish invasion or in anticipation of it, was nearest to his heart.
Actually he had been in London just before the meeting of the Parliament, trying to arrange for such "fiddling things"-- so Cromwell had called them--as shooting him in the Park or blowing him up in his chamber at Whitehall.

Before Thurloe had traces of him, he had again decamped to Flanders; but he had left a substitute in Miles Sindercombe, an old leveller and mutineer of 1647, but since then a quarter-master in Monk's Army in Scotland, and dismissed for his complicity in the Overton project.

Sexby had left Sindercombe L1600; and with this money Sindercombe had been again tampering with Cromwell's guard, taking a house at Hammersmith convenient for shots at Cromwell's coach when he drove to Hampton Court, and buying gunpowder and combustibles for a nearer attempt in Whitehall.

He had been, seen in the Chapel at Whitehall on the evening of January 8, and that night the sentinel on duty smelt fire just in time to extinguish a slow-match that was to explode a mass of blazing chemicals at midnight.

All Whitehall having been roused, the Protector with the rest, information led at once to Sindercombe.