The Parker Duofold Standard, along with the smaller Demi version, was the first Aerometric Duofold to be made in the Newhaven factory,1953. 

The U.K. Duofolds were made in 4 colours: black, blue, red, and green with green, this pen, being, by far, the least common.  At the time green was considered, by those of a superstitious nature, to be an unlucky colour so, it may well be that sales were limited for this reason.

The pen is in excellent condition, it has a bright surface, with no visible imprint. The  Gold filling to the clip and decorated cap band is pristine.  The clip is secured by a colour coded 'jewel'.

The original, correct, No. 25 14Ct. Gold nib is straight and well aligned, it carries a date code for 1959 and writes with a firm, fine line, well suited to someone with a small handwriting or for more detailed work. 

At 13.2 cm. capped and 14.7 cm. posted the Duofold is an average sized pen in terms of length but is a good deal 'fatter' than most, giving it a very solid, chunky feel.  This can be seen in the last photograph, which shows it alongside a contemporary Parker 51, itself not a slim pen by any means.

The Parker Aerometric Duofolds of the 1950s were excellent writing instruments which sold very well, despite the competition from the ballpoint.  Parker probably underpriced the pen in order to resist the pressure.  Sixty four years later the pen is still outstanding value, particularly when compared with a new Gold nibbed pen of similar quality.  It would make a very good vintage daily writer.