The turbines developed a total of 34,000 shaft horsepower (25,000 kW) and were intended to give a maximum speed of 35.5 knots (65.7 km/h; 40.9 mph).

[3] The ships carried enough fuel oil to give them a range of 5,500 nautical miles (10,200 km; 6,300 mi) at 15 knots (28 km/h; 17 mph).

For anti-aircraft (AA) defence, they had two quadruple mounts for the 0.5 inch Vickers Mark III machine gun.

On 27 June 1940, in company with Dainty, Defender, Decoy and the Australian destroyer Voyager she depth-charged the Italian submarine Console Generale Liuzzi off Crete.

[1] Also on 29 June Dainty and Ilex shared in the sinking of the Italian submarine Uebi Scebeli south-west of Crete.

[8] Ilex participated in the Battle of Calabria and on 19 June escorted Sydney during the sinking of the Italian cruiser Bartolomeo Colleoni off Cape Spada, rescuing 230 survivors.

On 14 June she suffered major structural damage from dive-bombing near misses during an operation to prevent interference by Vichy French warships.

In March 1945 the destroyer was towed to Malta for repair, and in April reduced to "reserve category C", the survey declaring her "not required for further operational service".