Peter Archer illustrated many of the Armada paperback covers
in the 1960s. He is credited as cover artist of several of their Monica Edwards titles.
He is credited as the cover artist of four: The Nightbird in 1963, No Entry and The Cownappers in 1964, and also of Cargo of Horses in 1965.
The credit on the last is an error: the cover was in fact painted by Mary Gernat, confirmed by the discovery of her original draft artwork.
There are inconsistencies in the different covers credited to him, including many of those in the late
1960s and 1970s which lead me to have doubts about the accuracy of the credits in other Armada paperbacks, including that for The Nightbird.