Lowerson's promotion to sergeant was made permanent while he was still recovering from his wounding at Bullecourt. He rejoined his battalion in November 1917. On 1 September 1918, during the Battle of Mont St Quentin, 21st Battalion supported 23rd and 24th Battalions in an attack towards the village of Mont St Quentin. Lowerson's company was held up in its advance on the flank of the village and, with a party of seven men, attacked and captured a strong point from which heavy machinegun fire was directed towards the advancing Australians. The advance was able to continue. Lowerson, wounded, was sent to the rear but it was a further two days before he was dispatched to a hospital.
After his wounding at St Quentin, Lowerson returned to his unit in September 1918 but received his fourth wound the following month and took no further part in the war. The award of his VC for his actions at St Quentin was gazetted on 14 December 1918 and he was presented with it by King George V on 1 March 1919. The citation for his VC read:
For most conspicuous bravery and tactical skill on the 1st September, 1918, during the attack on Mt. St. Quentin, north of Peronne, when very strong opposition was met with early in the attack, and every foot of ground was stubbornly contested by the enemy. Regardless of heavy enemy machine gun fire, Sergeant Lowerson moved about fearlessly directing his men, encouraging them to still greater effort, and finally led them on to the objective. On reaching the objective he saw that the left attacking party was held up by an enemy strong post heavily manned with twelve machine guns. Under the heaviest sniping and machine gun fire, Sergeant Lowerson rallied seven men as a storming party, and directing them to attack the flanks of the post, rushed the strong point, and, by effective bombing, captured it, together with twelve machine guns and thirty prisoners. Though severely wounded in the right thigh, he refused to leave the front line until the prisoners had been disposed of, and the organization and consolidation of the post had been thoroughly completed. Throughout a week of operations, his leadership and example had a continual influence on the men serving under him, whilst his prompt and effective action at a critical juncture allowed the forward movement to be carried on without delay, thus ensuring the success of the attack.
— The London Gazette, 13 December 1918