This set is date coded for 1951, making it one of the first 'aerometric' filling pens produced by Parker at the English Newhaven factory.
The Demi has the same girth as the standard Duofold giving it a noticeably 'chunky appearance. The shorter pens were probably made in response to a demand for a pen that would fit into a shirt pocket and allow the flap to be closed, a feature that was popular with the military.
The set is presented in the original Demi box, along with a matching propelling pencil, both are in excellent working condition.
This is a most attractive and practical set, the Demi is now quite collectable.