Calvert was 26 years old, and a sergeant in the 5th Battalion, King's Own Yorkshire Light Infantry, British Army during the First World War when, on 12 September 1918 at Havrincourt, France, at the Battle of Havrincourt, the following deed took place for which he was awarded the VC.

For most conspicuous bravery and devotion to duty in attack when the success of the operation was rendered doubtful owing, to severe enfilade machine-gun fire.

His valour and determination in capturing single-handed two machine guns and killing the crews thereof enabled the ultimate objective to be won.

His personal gallantry inspired all ranks.He was also awarded the Military Medal (MM),[2] and the Belgian Order of Leopold (with palm), in the grade of Chevalier.

His VC is on display in the Lord Ashcroft Gallery at the Imperial War Museum, London.