Commemorative cover issued to celebrate the 50th anniversary of Amy Johnson's solo flight from England to Australia

Commemorative cover issued by the Air Education & Recreation Organisation (A.E.R.O.) to celebrate the 50th anniversary of Amy Johnson's solo flight from England to Australia.
It is a cream coloured envelope with black printing which describes the reason for the cover and also lists the places in which Amy Johnson stopped at on her journey and information about her plane 'JASON'.
There is a coloured depiction of the plane with green fuselage, wheels and serial number, below which is a sepia portrait of Amy Johnson inside a green wreath.
The name of the designer, Brian Gaunt, and the number of the cover, 1801, appear below.
On the right hand side is a British postage stamp of 10 P denomination, featuring a kingfisher. The special oval postal mark also features the plane and has the date (2 June 1980) and place (Hull) of the release of the commemorative cover.
On the flap of the envelope there is a rectangular black stamp indicating that the cover was flown to Darwin and returned to London by Quantas [sic] in July 1980. This is certified with a written signature. On the right hand side is a red stamp with details of the airport in Surrey from which it departed.
At the bottom centre of the envelope flap is 'Cover 1' which may mean there were other designs in the series.