On 23/8/2002 Jean Christophe Carbonel published an article titled "asymétriques anglais" in Aeroforums, including an illustration on the airplane at the left. As per the German text in the magazine "Wissen und Fortschritt" it is a 1938 desing.
The address http://aeroforums.free.fr/forumtech/aff.php3?350 is not working anymore but the same drawing can be seen at http://www.geocities.com/asymmetrics/britishasymms.htm, together with an identification attempt by myself (in my opinion, it is derived from the Miles Master with two Kestrel XXX engines),
There was also an article at Le Fanatique de l'Aviation published at a later date, including same illustration but I do not have either the number or the date in my files.