Above: A 51 Aerometric Mk1 from the mid 1950s showing the shorter clip. Most 51s found in the UK are similar to this, with production running until probably at least the late 1960s

First Year 51 Vacumatics produced in 1941 differed in some respects from the 1942-48 production. The most obvious variations were that the barrel imprints were at the filler end rather than next to the clutch ring, and both jewels were metal rather than plastic The filling system was re-designed in 1948, with the introduction of the Aerometric filling system. This filling system operated by pressing a pressure bar on "Pli-Glass" PVC sac. [2] wanted’ – retaining its distinctive streamlined silhouette and iconic hooded nib; yet is made for the future – this pen is hand assembled and made from durable precious resin, benefitting from Parker’s expertise and reputation for superior craftmanship. The Parker 51 is a fountain pen first introduced in 1941. Parker marketed it as “The World’s Most Wanted Pen,” a slogan alluding to restrictions on production of consumer goods for civilian markets in the United States during World War II.The Vacumatic filling system was developed by Parker in the early 1930s. Ink is drawn in to the pen by repeated pushing of a plunger at the end of the barrel. This flexes a rubber diaphragm attached to the plunger with the partial vacuum drawing ink into the barrel. Ink is held directly in the barrel - the pen does not have a conventional ink sac Queen Elizabeth used a burgundy Parker 51 since the 1950s. [12] Parker as a company has received a Royal warrant of appointment as the official providers of writing instruments for the Royal Family. [13] Appearances in media [ edit ] The pen and the ink were both named "51" to mark 1939, the company's 51st anniversary, during which development for the pen was completed (U.S. design patent No. 116,097, U.S. Patent 2,223,541 filed). By giving the pen a number instead of a name, Parker avoided the problem of translating a name into other languages.

The 51 was a unique product and shook the world on its introduction. The torpedo shaped design and the hooded nib became icons of style and were copied by virtually every other pen manufacturer. It is no exaggeration to say that the Parker 51 is the most popular, reliable and functional pen ever invented. TheParker "51"stayed in production until 1972 with a series of revisions throughout its production cycle. The history of the pen is as follows, note that there is inconsistency amongst the experts about the names of the different types of 51, some regard the Vacumatic 51 as a seperate entity and the aerometric is the Mk I, I prefer to follow David Shepherds philosophy as outlined below; Lauren Hubbard. "Queen Elizabeth Has Used the Same Brand of Pens for Almost 60 Years". Town & Country Magazine . Retrieved 10 Jul 2021.In addition, Parker reformulated its "51" ink, reducing the alkalinity, and introducing a selection of bright colors, and changing its name to Superchrome. Like the"51"ink, it also came with a warning that it should be used only in the Parker51, though this warning was more discreet. Parker's continual advertising during the war created demand that took several years to fulfil after the end of the conflict. Above: The 51 Aerometric Mk2 introduced in the late 1960s featured a 61 style cap with plastic jewel, a slightly shorter barrel with flattened rather than rounded end amongst a number of other differences. Importantly, the front shell and barrel were still made from lucite with the barrel threading being the same as on the Mk1