In The Trick That Failed, Flight Lieutenant Rosten used what Johns called a "Jodel D2" to fetch his girl-friend Diana Fulvers. The only problem is that there is no D2. Jodel made a series of ultra-light monoplanes in France intended for amateur construction, starting with the single-seat D9 "Bebe". Later, at the request of the French government to provide an inexpensive aircraft for the many emerging flying clubs in France, Jodel designed the two-seat D11. There followed a series of variants with different and increasingly more powerful engines. However, the aircraft which Rosten used had a "forty-five horse Salmson radial" engine. The only Jodel which used this engine was the D11. The D11 first flew on 4 April 1950. It featured a fixed undercarriage and tailskid with side by side seating for two. The wing panels outboard of the landing gear had a marked dihedral. The aircraft was made almost entirely of plywood. Construction was extremely simple. The original D11 aircraft had no electrics and no wheelbrakes!
It is possible that Johns meant the D11 but the "11" part of the name was misread by someone, perhaps at the printing phase, and thought to be a Roman "II" which was subsequently rendered as "2".