This is a Parker 51 Vacumatic finished in Black with a Rolled Gold cap. It was made in the UK around 1945. The Vacumatic 51's are a lot less common than the later aerometric models and use the pump system borrowed from the earlier Vacumatic range.
The cap is finished in 1/10 12ct rolled gold and has the converging groups of lines pattern. The pen has been fully serviced and a new diaphragm has been fitted. It is fitted with a lovely smooth Medium nib and is in overall very good condition with light wear marks and scratches commensurate with use. There are no dings in the cap.