The following is an extract from the RAF History of Bomber Command:-
"No. 4 (Bomber) Group was formed on 1st April 1937, with headquarters at Mildenhall, Suffolk, and its first AOC was Air Commodore (as he then was) AT Harris, who was later to become AOC No. 5 Group and then, from 1942 to 1945, AOCinC Bomber Command. On 29th June 1937, headquarters were re-located at Linton-on-Ouse, Yorkshire, and on the same date the Group took over the following stations and squadrons from No. 3 (Bomber) Group: Leconfield, Nos. 97 and 166 Squadrons; Driffield, Nos. 75 and 215 Squadrons; Dishforth, Nos. 10 and 78 Squadrons; Finningley, Nos. 7 and 76 Squadrons; and Linton-on-Ouse, Nos. 51 and 58 Squadrons. Actually the last two squadrons were then located at Boscombe Down.
At the outbreak of war the Group had eight squadrons and its first operation was on the night of 3rd/4th September (the first night of the war) when ten Whitley IIIs of Nos. 51 and 58 Squadrons took off to drop leaflets in the Ruhr and over Hamburg and Bremen. From this small beginning sprang the vast and varied activity of the next five years. The Group not only struck many devastating blows against both Germany and Italy, but also trained many of the best crews in Bomber Command. In addition, it helped to create two other Bomber Groups."
On June 11 1940, the day after Italy entered the war, 36 Whitleys from 10, 51,58,77 and 102 Squadrons set off to bomb Turin and Genoa ,stagging through Jersey. Due to bad weather and engine failures due to icing only 13 aircraft reached their targets. I could find no evidence regarding what happened to those that did not make it.
Although the Whitley cannot be claimed to have been a success it was a great step forward from the aircraft it replaced i.e. HP Heyfords and laid the foundations for the RAF's night-bombing strategy and tactics.
I would Not say the aircraft was “built of cardboard”. It was the first aircraft with a stressed-skin to go into service with the RAF. See attached drawing showing it’s monocoque contruction.
Leonard Cheshire who, as a Flight Lieutenant on 102 Sqn and pilot of Whitley P5005 during a raid on Cologne in November 1940 received a direct hit from flak which ignited a flare and severely damaged the monocoque of the rear fuselage. Nevertheless, he continued to bomb the target before bringing the crippled aircraft home, for which he was awarded the DSO.