The ships carried a maximum of 500 long tons (510 t) of fuel oil that gave them a range of 3,850 nautical miles (7,130 km; 4,430 mi) at 20 knots (37 km/h; 23 mph).

Her light anti-aircraft suite was composed of one quadruple mount for 2-pounder "pom-pom" guns and four single Oerlikon 20 mm cannon.

Captained by Acting Commander James Hamilton Swain, during the course of this operation, Penn helped bring the damaged SS Ohio with her vital supplies of fuel into Grand Harbour, Valletta.

Commander Swain was mentioned in dispatches and was also awarded the Distinguished Service Order (DSO) for the part he played in Operation Pedestal.

On 7 November 1943 Penn with sister ship Pathfinder sank the German submarine trap GA45 off Amorgos, Greece.