There is actually a fair bit of information showing in the photograph.
He is wearing the
Imperial Service badge -
http://en.wikipedia.org/wiki/Territorial_Force_Imperial_Service_Badge - showing he served in a territorial battalion and had agreed to serve overseas. Wiki say it was introduced in 1912. Men enlisting in the first weeks of WW1 were also awarded it. If he enlisted before WW1 then he would have lived close to the HQ as he would have attended one evening a week
His cap badge is for a fusiliers regiment. Given where the photograph was taken it is likely he was in the London Regiment which comprised more than 20 Territorial battalions affiliated to various regiments, including the first four affiliated to the Royal Fusiliers -
http://www.1914-1918.net/london.htmOnce the original battalions were full they created a second line, and then a third line - 2nd/1st Bn, 3rd/2nd etc. These are listed lower down on the web page.
Unfortunately 9013 will not be his number. The TF were created in 1908 from Volunteer Battalions, and they started at number 1 again.
If you had family close to one of the districts covering 1st to 4th Battalions I would start there.
He has no rank chevrons, so a Private.
Ken