Sheffield was distantly related to lord president Sheffield, but his links went deeper than mere consanguinity: his great-aunt, Magdalen Frodsham, had spent years in the service of Lord Sheffield’s mother; while in 1615 he married the widow of one of the president’s sons.
Although not notably godly, Sheffield was one of those removed from the Northern recusancy commission in 1630, when its aims became fiscal rather than punitive. In 1634 he spent his second honeymoon at the Fairfax house in York, from where he lamented the news of the Protestant defeat at Nordlingen. It was perhaps with the encouragement of his Fairfax relatives that he signed the Yorkshire petition against billeting in July 1640, and three months later he was one of the unsuccessful candidates at Scarborough in the election for the Long Parliament.
Settling among the English community at Delft, Sheffield apparently remained sympathetic to the parliamentarian cause, warning Sir Ferdinando Fairfax of a plot to raise the North for the king in May 1646. In his will of 16 Apr. 1644, he left Mowthorpe manor (worth £117 per annum) to his stepdaughter’s child, and lands in the open fields at Epworth (annual gross value £26) to trustees for maintenance of the village schoolmaster. He named Fairfax and Sheffield, now earl of Mulgrave, as his executors, but on 25 Oct. 1646, after Mulgrave’s death, he nominated an English merchant at Rotterdam in his stead. He died the next day, the will being proved in London on 1 Dec. following.