They began by building the two despatch vessels, Mercury and Iris, with a speed not approached up to that date by any in naval service.

The First Naval Lord, Sir Astley Cooper Key, favoured an enlarged 15 knots (28 km/h) Comus class.

[10] "Lord Northbook's board were deeply impressed with the necessity for developing the construction of vessel of the Leander" type.

[7] "The first four ships of a large class laid down for the protection of commerce under Lord Northbrook's board were of the Leander type.

"Taking 14 knots as the standard of high speed, we have only 11 swift cruisers, counting the Iris and Mercury despatch vessels among them.

But the world is a large place; and eight or ten vessels cannot be everywhere, and the safety of our commerce imperatively demands that the swift cruisers which we have ready at the outbreak of a war shall be enough to clear the seas of privateers.

Much use, as a war goes on, may, no doubt, be made of the armed merchantmen on the Admiralty List; but we must have Royal [Navy] cruisers to begin with, A commencement was made last year by the late Board in the Leander and her two consorts, which, with their partially protected machinery, their great speed, and their excellent guns, will be everything that can be desired for the purpose for which they were devised.

Compared with the Iris class, the designers of the Leander "cut down top hamper and took advantage of the recent advance in gun construction to reduce the weight of, while adding to the efficiency of armaments.

At the previous six-hour' full power trial of the Phaëton there was a difficulty experienced in maintaining steam from want of draught in the stokeholds.

The trial was intended to have been for six hours, but during the eleventh half-hour, the expansion gear of the starboard engine heated and snapped, and the run was brought to a premature close.

As, however the machinery worked without any hitch of any kind, and was developing power largely in excess of the Admiralty contract, it was agreed by the officers superintending the trial to accept the means of the five hours as a sufficient test of performance.

In the 1888 British annual naval manoeuvres, "the proportion of untrained (2nd Class) stokers which were draughted to several of the ships appears to have been too large.

"[20] The Navy List gave the following composition of officers for the Leander in December 1885 (order as in the original):[21] Total 21 (including 4 engineers).

In March 1882, it was stated that "the Leander, the Arethusa, and the Phaeton will pass out of the hands of the contractors, and will come to our own yards to be completed and fitted with the new 6-inch breech-loader; and the Amphion, at Pembroke, will be pushed forward in the intervals of the iron-clad building.

[34] The explanation was that there had been a large increase in the expenditure for wages at the Dockyards, and this had paid for by money voted for the construction of the Leanders.

"[35] In May 1883, it was "alleged that one of the reasons for the delay in the construction of the Leander is that the Admiralty have not fully decided upon the smaller arrangements which have to be carried out by the builders."

Smith who said "the Leander class ought to be rendered complete, according to the arrangements undertaken by the Board of Admiralty, without loss of time.