As well as a significant historical 'first' this class also embodied many 'lasts' and, despite being units of the Edwardian-period Royal Navy, represented the end of the Victorian-period lineage of protected cruisers in many ways.

Discussions had been ongoing for several years about a successor to the previous Pelorus class before the Admiralty decided on a design in 1901 that was very much larger and faster than the older ships.

This represented a shift away from the traditional role of the third-class cruiser: previously best-suited to Imperial defence duties on foreign stations, but now shifting closer to the German concept of a light cruiser; a fast & potent small combatant, suitable for use with the Fleet for scouting duties in the presence of an enemy fleet.

In this regard, the Topaze class demonstrates the effect of heightening tensions between the British and Germans, as the Royal Navy's procurement programmes began to emphasise potential combat in the North Sea in anticipation of a possible future war.

The engines were designed to produce a total of 9,800 indicated horsepower (7,300 kW) which was intended to give a maximum speed of 21.75 knots (40.28 km/h; 25.03 mph).