Robert Innes Smith’s archive mainly comprises of his letters. Correspondents are predominantly British aristocrats and from aristocratic families (including the Queen, and the Duke of Norfolk) as well as politicians (such as Oswald Mosely) and historians. They also include other notable individuals such as the poet Sir John Betjeman, script writers Jimmy Perry/David Croft (Dad's Army, Are You Being Served?, 'Allo 'Allo!) and actors including Nyree Dawn Porter, (The Forsyte Saga).

Other items in the archive include newspaper cuttings, material relating to Burton Hall which was owned by Innes Smith, publications and photographs.