Mainstay of Bomber Command was the Whitley, which first entered service in March 1937 with 10 Sqn.

STRIKING POWER. Handley Page Hampden bombers of a type which composes a large portion of our bomber force. Although in service in large numbers the Hampden is still among the most efficient bombers in the world.
Last of the twin-engined bombers to go into RAF service during the expansion was the Handley Page Hampden bomber.

First production Spitfire Is at Eastleigh in January 1939. Jeffrey Quill, Supermarine test pilot, can be seen standing next to the chap in overalls.

The prototype Wellington Mk I bomber, L4212, taking off from Brooklands in December 1937. This aircraft was a complete redesign of the B.9/32, originally called the Crecy but changed to Wellington in September 1936.
The Vickers Wellington is built on the geodetic principle of construction, which confers high load carrying capacity and long range.

"Энсоны" 217-й эскадрильи в полете.
Avro Anson reconnaissance machines of the R.A.F. The Anson has prepared the way for the adoption of more powerful machines for coastal defence duties.
Photograph, taken by Charles E. Brown, depicts Anson Is of 217 Sqn, a general reconnaissance unit formed at Boscombe Down in March 1937, and based at St Eval until the war, patrolling the Western Approaches.

Vickers Vildebeests of 42 Squadron. The type was the RAF's only torpedo bomber at the outbreak of war.

Lockheed Hudson N7206 was evaluated by A&AEE before passing to 1 OTU and 6 OTU. It was destroyed when it hit some wires while low flying at Gainsford in May 1942. The first four RAF aircraft serial numbers N7205-8, were flown by the A&AEE.