Persia. (Air Mail Instructional). 1931. Registered Air Mail envelope addressed to Wrexham, Wales bearing Persia Yvert 524, 1c green and lilac, Yvert 531, 15c olive and blue, Yvert 534, 2k orange and violet and Air Mail Yvert 41, 10c ultramarine and red, Yvert 44, 1k turquoise and carmine and Yvert 46, 3k brown and green tied by Tehran double ring with hand-struck 'R/ Tehran' and boxed instructional 'Received Too Late/ For Inclusion in Air Despatch' on face in violet, endorsed 'Air Mail/ Teheran - London', routed via Bagdad with oval Registered/ Wrexham arrival.
The Air Mail instructional is not listed by 'Ian McQueen' in his hand-book 'Airmail Directional Handstamps.'