I am afraid I have little information on this aerogramme featuring Hadrian's Wall. The artist, Ronald Maddox also illustrated the 'Industrial Archaeology' set. He produced for Royal Mail during the 1960s - 80s. So does this rather modern (1990s/2000s?) aerogramme have a watercolour image on it that was actually sketched a few decades prior?
Thanks Ton! Centre top is Hadrian's Wall. These are from a booklet release for the International Festival of Philately. The stamps feature Roman engineering outside of Italy; the Segovia aqueduct, Pont Du Gard, Patrasso Odeon and the Black Gate. Issued: October 25 2009.
The wall on an 8v joint issue with Great Britain. The GB stamp has the same image, but is rated for 2nd class, not international. Issued: April 21 2005.
Front of the 1st booklet in the Roman Britain series with an aerial view of the wall. *Wanted, not in my collection.