Image 13-1 seems to have been Handley Page corporate artwork for a generic future bomber. Somehow, Flight confused this commercial art with the H.P.53 for Sweden. As Sheepster said on shipbucket.com"
"The above design was published in Flight magazine in May 1936. It appears to show an enlarged, single-tail, semi-swept wing Hampden potentially with Sabre or Vulture engines. This aircraft is described in the magazine as a development as the still-on-the-drawing board H.P.53 Swedish seaplane. This is before the issuing of Specification P.13/36 which eventually led to the Halifax, and I can find no other reference to the existence of this design???"