Just to tidy a few things up for you.
Christopher was born and resident Sheffield. He enlisted in Westminster.
The date of 14/11/15 is the date he landed in France, not the date he enlisted.
The actual medal roll should tell you which battalion he first saw active service with.
The Public School's and the Sportsman's battalions were all in 33rd Division and landed in France at the same time (Nov 1915). However, 23rd Battalion left for 2nd Division at the end of the month.
Although he died of wounds on 18/02/17, a total of 74 men from the 23rd Battalion were killed on the 17th Feb. Several others died of wounds in the following days. I think this is at Miraumont.
The war diary for 23rd Battalion Royal Fusiliers, covering November 1915 to July 1919, is held at Kew in WO 95/1372. It is also available to download from them at the very reasonable price of £3-50.
Phil