Members of the Middlesex Regiment in playing kit, 1915 (c).

Members of the Middlesex Regiment in playing kit, 1915 (c).

British troops who captured Tilloy, 10 April 1917.

British troops who captured Tilloy, 10 April 1917.

British and Indian wounded at Neuve Chapelle, 1915.

British and Indian wounded at Neuve Chapelle, 1915.

French troops don their gas masks, 1915 (c).

French troops don their gas masks, 1915 (c).

A soldier writing, Lievin, 1917 (c).

A soldier writing, Lievin, 1917 (c).

The Trench Kittens.

The Trench Kittens.

A soldier armed with a rifle grenade, 1917.

A soldier armed with a rifle grenade, 1917.

Soldier in trench, ‘GORDON ALLEY’ and ‘GOURLAY TRENCH.’

Soldier in trench, ‘GORDON ALLEY’ and ‘GOURLAY TRENCH.’

A Mark I tank surrounded by troops of 122nd Brigade, 1916.

A Mark I tank surrounded by troops of 122nd Brigade, 1916.

A soldier writing, Lievin, 1917 (c).

A soldier writing, Lievin, 1917 (c).

A soldier armed with a rifle grenade, 1917.

A soldier armed with a rifle grenade, 1917.

Soldier in trench, ‘GORDON ALLEY’ and ‘GOURLAY TRENCH.’

Soldier in trench, ‘GORDON ALLEY’ and ‘GOURLAY TRENCH.’

German prisoners at Dernancourt, 15 September 1916.

German prisoners at Dernancourt, 15 September 1916.

Turkish prisoners being marched to a camp at Cape Helles, 1915.

Turkish prisoners being marched to a camp at Cape Helles, 1915.

French infantry in a trench, 1914.

French infantry in a trench, 1914.

American soldiers from the 11th Engineer Regiment, 1917.

American soldiers from the 11th Engineer Regiment, 1917.

Mark I tank and infantry, 1916 (c).

Mark I tank and infantry, 1916 (c).

Mark II tanks, 1917.

Mark II tanks, 1917.

British troops who captured Tilloy, 10 April 1917.

British troops who captured Tilloy, 10 April 1917.

Royal Engineers repairing a bridge.

Royal Engineers repairing a bridge.

White City', located near Beaumont Hamel on the Somme, 1916.

White City’, located near Beaumont Hamel on the Somme, 1916.

The British Expeditionary Force Landing in France, August 1914.

The British Expeditionary Force Landing in France, August 1914.

Reinforcements... St Julien', 1917.

Reinforcements… St Julien’, 1917.

British troops near Boesinghe, 18 August 1917.

British troops near Boesinghe, 18 August 1917.

Soldiers leaning on a pile of 18-pounder shells, Somme 1916.

Soldiers leaning on a pile of 18-pounder shells, Somme 1916.

Lorry transport on the Somme, September 1916.

Lorry transport on the Somme, September 1916.

British wounded at an Advanced Dressing Station, 1916.

British wounded at an Advanced Dressing Station, 1916.

Horses picketed on the beach, 1915.

Horses picketed on the beach, 1915.

Church service on HMS 'Queen Elizabeth', 1915.

Church service on HMS ‘Queen Elizabeth’, 1915.

Members of the Inns of Court OTC at Berkhamstead, 1914.

Members of the Inns of Court OTC at Berkhamstead, 1914.

No. 3 Company, Public Schools Battalion, Ashstead, August 1914.

No. 3 Company, Public Schools Battalion, Ashstead, August 1914.

Private Percy Ottley, The London Scottish, 1916 (c).

Private Percy Ottley, The London Scottish, 1916 (c).

Cpl Thomas Gordon, 1918 (c).

Cpl Thomas Gordon, 1918 (c).

Pte William Henry Webb, 9th Bn Durham Light Infantry 1915-16.

Pte William Henry Webb, 9th Bn Durham Light Infantry 1915-16.

Indian soldiers in a trench, Gallipoli, 1915.

Indian soldiers in a trench, Gallipoli, 1915.

Using a trench periscope, Gallipoli, 1915.

Using a trench periscope, Gallipoli, 1915.

Cardinal Bourne visits Irish troops at the Front, 1916 (c).

Cardinal Bourne visits Irish troops at the Front, 1916 (c).

Our reserves awaiting orders to move up...', 1915.

Our reserves awaiting orders to move up…’, 1915.

General Hunter Weston & two of his Staff outside dug-out, 1915.

General Hunter Weston & two of his Staff outside dug-out, 1915.

French and British soldiers on the Somme, 7 July 1916.

French and British soldiers on the Somme, 7 July 1916.