For the 1908–1909 shipbuilding programme, the
British Admiralty decided to revert to a smaller, more affordable destroyer to follow-on from the large and fast (required to reach ) and the experimental . The destroyers needed sufficient range to operate across the
North Sea in the event of a confrontation with Germany, which rendered the coastal destroyers which had been built as a low-cost supplement to the expensive Tribals outdated, requiring larger numbers of a cheaper standard destroyer. While the Tribals were oil fuelled, it was decided to return to the use of
coal for the new destroyers, because of concerns over the availability of
oil stocks in the event of a war and to reduce costs. They were the last British destroyers to be so fueled. The
Beagles were not built to a standard design, with detailed design being left to the builders of individual ships in accordance with a loose specification. They were between and long
between perpendiculars, with a
beam of between and , with an average
draught of . It was expected that the ships would
displace but the builder's designs came out heavier, Three funnels were fitted. The
Beagle class was designed to carry a gun armament of five 12-pounder (76 mm) guns, with two mounted side by side on a raised platform on the ship's
forecastle, two on the ship's beams, with the port gun mounted ahead of the starboard gun and one aft. While the ships were building, however, it was decided to replace the two forecastle guns by a single gun, giving a gun armament of one
BL 4 inch naval gun Mk VIII and three
QF 12-pounder 12 cwt guns) Torpedo armament consisted of two
torpedo tubes, with one between the ship's
funnels and the aft gun, and one right aft at the stern of the ship. These torpedoes had a range of at or at . Two spare torpedoes were carried. Wartime modifications included replacement of the aft torpedo tube by a
3-pounder (47 mm) anti-aircraft gun in some ships, The
Beagles were followed, in the 1909–10 Programme, by the (later known as the H class). ==Service==