The Derwent 1 was designed to the same diameter as the Welland as it had to fit the same Meteor nacelle. It was designed to produce 2000lb thrust and it incorporated a straight-through gas flow system.
Drawings started in April 1943 and it passed its 100 hour test at 2000lb rating in November 1943.
In April 1944 it went through flight tests in a Meteor rated at 1800lbs thrust and with a weight of 920lbs.
The Derwent II, III and IV followed. When the Derwent V was developed, it incorporated so many changes in design that it was virtually a new engine. It provided the increase in power needed to power the larger and heavier Meteor night fighter aircraft.