Volumes 1-11 the period 25 Feb 1860-29 Dec 1884 and are for visitors to the public Galleries. Volumes 1-10 give the date, and the signatures of visitors to the Gallery, along with the numbers included in group visits, and the daily totals. Volumes are arranged in chronological order. Volume 11 gives this information for 1 Dec 1869-15 Dec 1869, then includes summary lists of numbers of visitors at key holidays - Easter, Whitsun, and Christmas - for 1870-1884.
Volume 12 covers the period 28 Feb 1896-31 Mar 1920 and is mainly for researchers, conservators, or those visiting the Director on business, giving the names, addresses, and subjects of visit.
Volume 13 covers the period 1933-1951 and is for special events such as opening ceremonies, and includes the signatures of Royalty and other guests present at these occasions.
Visitor books were not kept for 1885-1895, while the Gallery was at the Bethnal Green Museum, because entrance was to that museum as a whole, rather than the National Portrait Gallery specifically. In 1896, on the opening of the St. Martin's Place premises visitor books were discontinued and replaced by turnstile account books (NPG73).