Compare your cap with a 51 pencil (or 61 fountain pen). The VIP jewel is the same diameter as a 51 pencil/61 FP. 61 pencils and ball points have a more tapered cap and a smaller jewel. The VIP actually uses a 61 fountain pen clip.
Just found one. Way earlier than I imagined. The barrel has a 1950 date code on the second line of the partially visible imprint shown above. The slotted "cap" under the nib polishes like silver. Now to find a set of directions.