George Mackereth married in the late summer of 1879 in the Ashton under Lyne area. It is uncommon name and the family history website, FreeBMD, only lists the birth of two other children before Egbert's in 1885. Kate Mackereth was born in 1880 and Robert in 1883 - they were, most probably, his brother and sister.
In 1912, Egbert married his fiancée, Jeanie Elizabeth Walker. The service was held at the Independent Chapel on Ashton Hill Lane in Droylsden. He is commemorated on the High Lane War Memorial and is known to have lived for a period at Windlehurst. In the September quarter of 1914, the birth of Donald Walker Mackerereth was registered at Hazel Grove and was, almost certainly, their son. At the time of his enlistment into the army he was living with Jeannie in the Fairfield area of Manchester, probably at 7 Healey Terrace where she is known to have been living in the 1920s.
When Egbert enlisted into the army at Ashton, he was assigned to the Oxfordshire & Buckinghamshire Light Infantry (service number 31320) and went overseas on active service with them. At some point, perhaps after recovering from wounds or illness, Egbert was transferred to the Worcesters.
On 9th April, the Germans launched the second phase of their spring offensive and, as the month before, there was overwhelming success with the British being driven back along miles of the front. However, by the end of the April, the attacks were petering out. On the 26th, Egbert and his comrades were ordered to make a counter-attack in the direction of the Belgian village of Kemmel. It was successful in their sector, but other units had met with much greater resistance and the Worcesters later had to withdraw.
On the night of 29/30 April, they took over a section of the front line, relieving a battalion of the Yorkshire Light Infantry. The Battalion's War Diary entry for the day is brief "Bn sniped continuously and shelled intermittently during the day". The fact that Egbert has no known grave might suggest that he become a victim of one of the exploding shells and there was nothing left of him to bury.
There is some further information about Egbert in the book "Remembered" by P Clarke, A Cook and J Bintliff.