The only info I have about occupation is from a press cutting about George's brothers, who are all in the services. It says "George (who works for Messrs. Wray & Fuller) has joined up under Lord Derby's Scheme."
A scan using a popular search engine indicates that Wray & Fuller were a builders merchants and 'monumental masons' in Springfield Road, Chelmsford.
Here's the cap badge.
There was nothing to stop George volunteering to enlist under the Derby Scheme in 1915, which pre-dated conscription of 1916. Men were also encouraged to join their local VTC unit in order to get some basic form of military instruction before being called forward as Derby scheme members, but again this didn't begin until January 1916. However he may have been rejected for military service when his Group was called forward and either opted to either join or remain in the VTC(if he was already serving with them.).
By the way the photo is a beauty.