The Admiralty design was based on the preceding L class but modified to produce an increase in speed by approximately 6 knots (11 km/h; 6.9 mph).

Three destroyers already under construction were purchased from Yarrow, two from Thornycroft and two from Hawthorn Leslie to these builders' individual designs, and these are listed in separate articles.

The funnel heights were also raised compared with the pre-war vessels, and the second 4 in gun was mounted on a bandstand, as with the earlier L-class destroyers.

Partridge, Norman, Maenad, Ophelia and Observer were later fitted to carry a kite balloon.

Sixteen vessels were ordered in September 1914 (as well as four of the Yarrow M class), but part of their cost was met by the provision in the 1914–15 Programme for ten destroyers.