Clicked on one of the links at the copyright site and this info came up, so it was the poster included in the kit not the plans:
[TABLE]
[TR]
[TH]Type of Work:[/TH]
[TD] Entry not found.[/TD]
[/TR]
[TR]
[TH]Registration Number / Date:[/TH]
[TD] TX0000622005 / 1981-02-02 [/TD]
[/TR]
[TR]
[TH]Application Title:[/TH]
[TD] Spitfire.[/TD]
[/TR]
[TR]
[TH]Title:[/TH]
[TD] Supermarine Spitfire / research, art, and design Bill Polvogt.[/TD]
[/TR]
[TR]
[TH]Imprint:[/TH]
[TD] [s.l. : s.n.], c1981.[/TD]
[/TR]
[TR]
[TH]Description:[/TH]
[TD] Poster.[/TD]
[/TR]
[TR]
[TH]Series:[/TH]
[TD] Famous aircraft series number 1 ; [v. 1, no. 5][/TD]
[/TR]
[TR]
[TH]Copyright Claimant:[/TH]
[TD] Bill Polvogt[/TD]
[/TR]
[TR]
[TH]Date of Creation:[/TH]
[TD] 1981[/TD]
[/TR]
[TR]
[TH]Date of Publication:[/TH]
[TD] 1981-01-15 [/TD]
[/TR]
[TR]
[TH][/TH]
[TD][/TD]
[/TR]
[TR]
[TH]Other Title:[/TH]
[TD] Famous aircraft series number 1 ; [v. 1, no. 5][/TD]
[/TR]
[TR]
[TH]Names:[/TH]
[TD]
Polvogt, Bill, 1929- [/TD]
[/TR]
[/TABLE]