It’s a Parker button filler. It has an aluminium button like an AF. The cap is smooth steel with a tapered clip marked “Parker”. The nib is Canadian. The dark blue barrel has no imprint. The section is transparent.
Edit to add: Thanks for the help. It appears to be a Parker VS Mark II from the early part of 1948 before they changed to Aerometric fillers. The clear feed is from the earlier model.