After the Battle of Britain Lock served on the Channel Front, flying offensive sweeps over France. Lock went on to bring his overall total to 26 aerial victories, one shared destroyed and eight probable in 25 weeks of operational sorties over a one-year period, during which time he was hospitalised for six months. Included in his victory total were 20 German fighter aircraft, 18 of them Messerschmitt Bf 109s. In mid-1941 Lock was promoted to the rank of flight lieutenant.