He also served as High Sheriff of Nottinghamshire for 1634 and then as Lieutenant of the Tower of London, from December 1641 to February 1642.

When the Civil War started, he joined the king at York and soon afterwards was commanding a troop of Nottinghamshire Trained Band Horse at Newark-on-Trent.

He then marched with Prince Rupert's forces into Yorkshire and commanded the royalist right flank at the Battle of Marston Moor in July 1644, but after his troops were routed by numerically superior parliamentarian forces he retreated to Carnarvon and resigned his command.

He did, however, defend Carnarvon Castle ably for the Royalist cause, withstanding long sieges before finally surrendering it to Parliamentary forces in 1646.

Eleanor was famous for her beauty; Peter Lely painted her as St. Catherine, as depicted here; and according to the diarist Samuel Pepys she was the 17th mistress of Charles II.