 Complete the following phrase:  Ledbury was engaged in escorting major warships and Fleet auxiliaries in the North Sea until late June 1942, when she was attached to the ocean escort of the convoy PQ 17. Mariners that took part in convoys delivering supplies to Russia remember vividly the biting cold and the continual fear of attack by air or sea. The supplies were vital in that they were needed to keep Russia in the war following her 