In Biggles Takes a Hand, the Adlon Restaurant was German restaurant in Bank Street, Kensington. From Biggles' point of view, it was a small, unprepossessing establishment typical of thousands in London. However he later found the food to be good and the prices not quite as cheap as might be expected.
Von Stalhein used the restaurant often, and there he first spotted the gang of professional assassins headed by Ludwig Karkoff who had arrived in Britain on the trail of the Roth family. Using an anonymous note, von Stalhein invited Biggles for a meal at the Adlon so that he might recognise the gang members.
The Adlon Restaurant is a fictional location and so is Bank Street in Kensington.