Thanks to BRONNO we now know that the Officer is Henry NEWTON.

• 2nd Lieut. 1st Volunteer Battalion The Sherwood Foresters, 28.4.1906.
• Lieutenant 5th Battalion, 18.9.1909 and Captain 17.11.1912.
• Lieut-Colonel and O.C. II Army R.E. Workshops 1915-17.

Confirming that this is a picture of the 5th (Derby) Battalion, Machine Gun Section taken in 1912.