The Parker Duofold Pen
The fountain pen dates back to the 1880s in the USA. George Safford Parker, a school teacher from Janesville, Wisconsin, fed up with constantly having to repair the pens of his students, patented his own pen design in 1889. The Parker Pen Company was formed in 1892 and by 1899 Parker was selling pens to the public and the armed forces.

The Parker Duofold fountain pen
In 1921 the company introduced the Parker Duofold fountain pen. It was an immediate success. Sir Arthur Conan Doyle used one to write the exploits of Sherlock Holmes. By 1926 the Duofold was being made in plastic, allowing Parker to increase its guarantee from 25 years to "forever" and bring in new colors including Jade Green, Mandarin Yellow, and Lapis Blue. The arrow-style clip, designed by New York artist Joseph Platt, appeared in 1933 and has become Parker's distinctive trade mark.
General Douglas MacArthur signed the document ending World War II in the Pacific with his 20 year old Duofold. The Armistice ending World War II on the European Front was signed with Parker 51 pens (left) belonging to General Dwight D. Eisenhower. The Parker 51, introduced in 1941, had a slimmer design than the Duofold, and a hooded nib. In 1950 it received the Fashion Academy Award for exceptional styling, precision, and craftsmanship.
The Parker Jotter Ball Pen appeared in 1954 and the T-ball Jotter (1957) remains an industry standard. The famed styling of the Parker Duofold was revived in 1972 as a ball pen under the label Big Red, millions being bought by people who nostalgically recalled the Roaring 20's.
The Duofold Centennial
The Duofold design was reintroduced in 1987 as the Duofold Centennial Fountain Pen and Ball Pen in anticipation of Parker's 100th anniversary. Combining traditional classic pen styling with state-of-the-art writing technology, it was again an immediate success.

My Parker Duofold Centennial pen
A 23ct gold plated, a sterling silver, and a marbled green were added to the luxurious Duofold line in 1991. I was given a marbled one as a Christmas present in the early 1990s. At first, the ink didn't quite flow as well as the Sheaffer I'd previously been using so I sent the Duofold to Parker, who adjusted it and sent it back a few days later in perfect working order.
The Parker Duofold hasn't changed much in 84 years. Left is an early original, which apart from the addition of some gold bands and the arrow-style clip, is pretty much the same design as the modern version shown at the top of the page. This, together with the fact that the Duofold is an excellent pen to write with and is beautifully made, is why it's a design classic. The design has been imitated but this is the de facto classic fountain pen. If anything, the Parker 51, which was heralded as a futuristic design when it was introduced, looks more dated than the timeless Duofold.