My maternal grandfather, Cecil Bert Cooper, born 28 Jul 1885 in Heigham parish, Norfolk, England, UK, took part in WWI, according to the following quotation:

"In the meantime the clouds of war were looming over Europe, and in early August of 1914, war was declared between Germany and the European Allies. Of course in those days there was no worldwide Radio service, and it was not immediately known in South Africa. As soon as it was, the Government declared in line with the other Dominion governments. It was obvious that the real action was going to be in Europe, so Dad resigned his job in Johburg, went down to Capetown, and got a berth on the first ship he could, sailing for England. On arrival he joined the Royal Engineers as a Sapper. After an initial period of military training he was sent to the Western Front in France. He was to spend the next four years, except for short breaks of leave in Blighty, in the dreadful conditions of the trenches. By late 1916 he had been gassed twice, and been awarded the Military Medal for bravery in the face of the enemy. In 1917 he was commissioned in the field as a subaltern in the Royal Engineers."

Can anyone suggest where I can obtain records of his service and awards while fighting in France?