 After work-up, "Onslow" joined the 17 Destroyer Flotilla as leader.On 24 November 1941, "Onslow", together with sister ship and the cruiser , joined Arctic convoy Convoy PQ 4, escorting the convoy until being relieved by locally-based ships on 27 November.The convoy continued on to Arkhangelsk, while "Berwick", "Onslow" and "Offa" proceeded to the naval base at Murmansk.