The success of the Moth put too much pressure on the factory at Stag Lane. The area was becoming enclosed by the expanding London suburbs. A new site was needed and after careful searching land was purchased at Hatfield, Hertfordshire, in 1930. Farm land was also acquired to prevent encroachment by housing. By 1932 production had moved to the new factory. In January 1934 a Notice To Airmen (NOTAM) announced the closure of Stag Lane but it was not until 28 July that de Havilland took off in a Hornet Moth in the last flight from the airfield.

The company did not concentrate exclusively on private aircraft. The success of the Fox Moth single-engined airliner prompted requests for larger aircraft which developed into a series of multi-engined biplane passenger carriers. The first, the Dragon, was powered by two Gipsy Major engines. It was originally designed for the Iraqi Air Force but found popularity with airlines worldwide. The four-engined DH.86 was used by Qantas, Imperial Airways and other airlines on routes over water. The Dragon Rapide, later known simply as the Rapide, was a smaller version of the DH.86. It was one of the most successful airliners and powered by two Gipsy Six engines. It made its maiden flight at Hatfield on 17 April 1934 , one of the first aircraft to do so, and remained in production until the end of World War Two. The last of the twin-engined biplanes, the Dragonfly, was designed for luxury touring and expected to appeal to the rich. It too, however, was adopted by airlines which appreciated its qualities and bought many examples.

As time passed de Havilland’s role within the company had changed. His age and the complexity of modern aircraft meant that he could no longer do as much test flying as he had and that aircraft design had to be handled by a large team.

In 1934 the first Comet racer flew only six weeks before the start of the MacRobertson race from London to Australia . Arthur Hagg, the Chief Designer, had developed a new method of wooden construction which produced a strong, light aircraft. Three were entered in the race, one of which was the winner. Two more were built later; one as a high-speed mailplane and the other for record breaking.

The success of the American airliners in the MacRobertson race made de Havilland realise that the airline market was changing. He was able to get backing from the Air Ministry for the construction of two Albatross high-speed experimental transatlantic mailplanes. Halford designed the Gipsy Twelve engine and four were used in the new aircraft. Construction was similar to the Comet racer. The type first flew in 1937 and entered airline service in 1938. Few were built, but the sleek design represented the pinnacle of British wooden aircraft design to date.

For the Flamingo twin-engined airliner R.E. Bishop employed a type of construction, stressed metal skin, which de Havilland had never previously used. It was ordered by airlines and the RAF. It entered service with the RAF and British Overseas Airways Corporation during World War Two.