This is a Parker 51 Aerometric MkIII finished in Grey with a Lustraloy Gold Cap. It was made in the UK and is an excellent example of this very popular model from the early 70's.
The pen is fitted with the reliable aerometric filling mechanism which has been fully serviced. It is fitted with a superb smooth Broad side of Medium 14ct gold nib and is in overall very good condition with minor wear marks commensurate with light use. The Lustraloy cap is ding free.
This is the MkIII model with the thin clutch ring and the flat barrel end, they were only made between 1969 and 1971 so they are relatively rare.