These Parker 61 Ball Pens are quite rare in this condition, probably because most of them were used extensively, they were reliable and of exceptional quality.
This one is in very good condition, it is the 61 CT (Chrome Trim) model finished in Grey with a Lustraloy cap. The pen has only very light marks and scratches commensurate with light use. The mechanism works perfectly and the pen takes standard Parker ball pen refills which are still readily available. The original chalk marks are still on the barrel.
This is the Mk1 61 with the Pearl jewel in the clip screw.