Sophie Sulehria
BBC News, Bedford

At the Higgins museum, external:

While the lights are out, letters written by visitors tonight hang inside the museum. They are written to friends, family or an unknown soldier who fought in WW1. Just one light remains on as people read poetry and letters.

In Wales, commemorations are being led by a national service of remembrance at Llandaff Cathedral in Cardiff.

News from 1914
The world on the brink of war

Image source, Getty Images

Shell-shocked soldiers

Soldiers who served in World War One endured some of the most terrible forms of warfare ever known. They witnessed death and mutilation caused by exploding shells, machine guns or silent but deadly poison gas. During the war 80,000 men were diagnosed with shell shock.

Blackpool Tower joined the lights out event:

The vigil at Westminster Abbey is under way. Here is the order of service, external.

The BBC's Sarah Jones has taken this picture of the light installation in London behind Westminster Abbey.

Lights are being switched off at some of the UK's most famous buildings:

Image source, ALAMY

A single candle stands outside Downing Street. An hour's darkness will mark 100 years since the beginning of World War One, recalling the words of Sir Edward Grey at the start of the war in 1914.

News from 1914
The world on the brink of war

Image source, Howard Payton and Martin Cree

Ten Brothers sent to the Front

Alfred Pope ran a successful business in Dorchester, Dorset. Like most families in Britain, World War One was to take its toll on his family.

Ten of father Alfred's sons saw active duty in the war - and three of them died. Of Alfred's four daughters, three of them were actively involved with the Red Cross and nursing in Dorchester. The other daughter became one of the country's thousands of widows when her husband was killed in action.

Ben Maeder
BBC Radio Cumbria

Some of the lights have already been lit by members of the Royal British Legion on the cenotaph in Whitehaven's Castle Park.

Later a male voice choir will sing songs from the First World War, and organisers have encouraged locals to bring their own lights and candles to the service. It's thought 622 Whitehaven men lost their lives in the Great War.

Nick Higham
BBC News

St Symphorien military cemetery was the perfect venue for what was billed as an "event of reconciliation".

Princes and politicians, soldiers and civilians came together to remember: enemies a century ago, allies now.

They read from the letters and diaries of those who'd fought and died. Musicians from the London Symphony Orchestra and the Berlin Philharmonic under Sir Simon Rattle played Brahms' German Requiem and the music of George Butterworth, killed on the Somme.

And as dusk fell they laid wreaths at the foot of an obelisk among the trees erected by the Germans in honour of the British dead, in a ceremony that was beautifully conceived and executed.

News from 1914
The world on the brink of war

Image source, IWM

The Angel of Pervyse

Born in Exeter, Elsie Knocker lived and worked metres from the front line in Belgium. She set up a first aid post in the cellar of a house near Ypres with her friend Mairi Chisholm. Their work so close to the battlefield was recognised internationally and they became celebrities of the conflict.

Known as the angels of Pervyse, their fame enabled them to return to Britain to raise funds to continue their front line first aid.

Tom Bayly
BBC News, at Westminster Abbey

Among the well-known faces seen entering the Abbey; actors Mark Gatiss and Penelope Keith, former Health Secretary Andrew Lansley, Deputy Labour Leader Harriet Harman, and Birdsong author Sebastian Faulks.

News from 1914
The world on the brink of war

Image source, Getty Images

The Unknown Soldier

In memorials to previous wars the ordinary soldier was seldom remembered. During the First World War a British chaplain, the Rev David Railton, was struck by the sight of an anonymous grave in Northern France. He made it his mission to find a way to commemorate all the unknown soldiers who lost their lives in the war.

Julia Moore
BBC News, at Guildford Cathedral

People are beginning to arrive for the candle-lit vigil. The Earl and Countess of Wessex are expected shortly.

Here are selections of the many fascinating tweets, external shared under #Remember and posts on Facebook, external sent during the day's commemorations

News from 1914
The world on the brink of war

Image source, Ron Davies

What a beauty

Mules and horses provided the backbone of the vast logistical operations of armies on both sides.

During the conflict the British Army deployed more than a million horses and mules. One such horse was Beauty, the grocer's horse from Minsterley, Shropshire. Beauty would have been trained in a remount centre nearby, and from there sent overseas.

History doesn't relate what became of Beauty but it's unlikely he was returned to his owner. Many were sold abroad to work on farms or for meat.

News from 1914
The world on the brink of war

Image source, Museum of English Rural Life

The Women's Land Army

As men from the farming communities headed to war, women were required to work the land and keep food supplies maintained. Across Britain women workers did a range of tasks including milking, ploughing, herding and other heavy work. By 1918, there were 23,000 women working in the fields.

At Goring Heath Farm, on the Berkshire border, women ploughed the land and gathered in the harvest. Hear the WW1 memories of Kathleen Gilbert.

"The lamps are going out all over Europe; we shall not see them lit again in our life-time." Those were the words of Foreign Secretary Sir Edward Grey on the eve of war. Details of "lights out" events taking place across the country are here, external or at www.1418now.org.uk.

Jennie Dennett
BBC Radio Cumbria

In Barrow, white crosses are placed at St Mark's church for the 128 fallen of the Central parish. "Each cross represents not just an individual but a shattered family", Lay Preacher John Hazlehurst says.