Wrapped up well in the Trenches

The evidence of Photo 2 (left - click on image to enlarge): 

Sandbags: This photo shows a sandbagged trench. Sandbags were difficult to come by in 1914 so this suggests a later date. Sgt DAB Marples describes how the Germans shot at the sandbags at close range to break them down and reduce the cover that they gave.

Headdress: As the glengarry with diced (chequered) banding is still the headress of choice but soldiers are still in gloves and greatcoats, this suggests Spring 1915. The soldier to the left in the standard peaked cap is not of The Liverpool Scottish but may be a member of an English battalion coming into or going out of the trenches, an artillery officer or possibly Lt Kidson RAMC. Quite quickly, the stiffening was taken out of the peaked cap as the very flat surface was more easily spotted from the air. Alternatively he might be one of the few Army Service Corps or Medical Corps soldiers attached to the battalion although the binoculars and the location in what appears to be the front line make this unlikely. This particular soldier is well wrapped up against the cold by his scarf; the binoculars that he carries may indicate that he is an officer or a senior NCO. The other officer is the company commander, Capt AS Anderson.

Relief:  This is the term used to describe the operation when one group of soldiers replaces another group at a particular position. The 'relief' of one battalion by another in the front line is a difficult operation. At the early stages of the war (when there were few communication trenches) it was particularly dangerous. One method was for the new battalion to cross in the open to their new trenches, line up behind and drop in. The outgoing soldiers then climbed out of the back of their trench into the open. This was rather noisy and dangerous for troops in the open but it did give people a chance to find out about the trenches from the previous occupants. An alternative was for the new soldiers to move in at one end while the other soldiers left at the opposite end.  There was more protection from the enemy but the new soldiers found out nothing about the new trenches which would almost certainly lead to casualties from snipers.