The Parker 51 Custom differs from the Classic in that it has a rolled Gold cap, whereas the classic cap is 'Lustralloy'.
In 1957 Parker stopped pencil dating on pencils and in 1958 added a 'halo' to the cap. this pencil has no date code, the imprint is crisp and clear, and the caps have no halo so the set can be dated to 1957.
The set has been fully serviced and tested, it is in excellent working condition. The back lucite bodywork has a first class surface and the imprints are crisp and clear. This is very unusual, particularly as the pen imrints are just below the clutch ring and wear quite readily. The original 'pli-glass' ink sac is also not ink stained, suggesting the set has seen little use. There is one very small, almost imperceptible shallow crease on the back of the pen cap but the caps are otherwise in first class condition. They are stamped '1/10 12Ct. R. Gold', meaning that they are 1/10, by weight Gold.
The pencil is a continuous feed type, pressing the cap extends the lead with a manual retract whilst holding the cap down. The eraser rubber has sheared off, the rubber becomes britlle with age. The grooves in the pencil cone are gold filled, consistent with a custom pencil.
The pen fills well and, as expected from a Parker 51, is a very good writer. The nib is unusual in that it has a left oblique stub profile which produces a difference in the thickness of the horizontal and vertical strokes and further variation by rotating the pen angle. Oblique nibs are virtually non existant on modern pens, it is a purely vintage feature, offered at a time when writing was taken seriously.
The hooded design of the 51 precludes any flexibility in the nib so line variation can only be obtained using a stub nib, particularly if it is oblique. A little experimentation with the pen would allow someone with a decent 'hand' to add character and produce very impressive results.
The box, which has some light age spots is the correct Parker 51 'Mock Croc' version, used, in England, between 1956 and 1959.
The Parker 51 is often referred to as the best pen that Parker ever made, it is certainly the most successful pen by any manufacturer and carries a great deal of prestige.