Lasted longer than I thought it would!
I would have accepted XP-1 or P-X, as well as P-1 (which is the production model, although strictly speaking the silhouette was of the prototype)
On that basis I feel I should award it to RR who came up with P-X before LM came up with P-1.
Correction to above, as RR edited his post to reflect P-X just as LM identified it as the P-1.
So with RR's agreement, LM has control as P-1 was one of the identies I would accept.