“The horse” is a frequent meeting place for people heading to Durham Market Place. But many people, even lifelong locals, don’t know who the double-life-sized equestrian statue represents. That ends here: The chap on the horse, clad in military regalia, is Charles William Van Stewart, the 3rd Marquess of Londonderry. The Marquess was a cavalryman in both the French Revolutionary Wars and the Napoleonic wars. He led a brigade of hussars (light cavalry) and served as the right-hand man for the Duke of Wellington. When the Marquess died in 1854,…