The moderator of the General Assembly of the Church of Scotland and his wife will attend a service this weekend to mark centenary of the Battle of Arras.

The right rev Dr Russell Barr will lead prayers at the service in the French town on Sunday in memory of the 159,000 allied soldiers who died during the six-week battle during the First World War.

His wife Margaret Barr plans to lay flowers on the grave of her great-uncle, who was one of 18,800 Scots killed in the fighting.

Private David Wyllie died of gunshot wounds at the age of 29 on April 24, 1917.

He had joined up at the age of 27 in June 1915, even though as a farm worker he was exempt from service.

Mrs Barr said: "It's a huge privilege to go out to Arras and represent the family, and to lay a wreath.

"It will be quite poignant. I will go and see his grave at Duisans cemetery and lay flowers there.

"I think my father would be very proud and happy that one of his family will be there at the ceremony. It will be a very emotional day."

Mrs Barr has carefully preserved photographs of her great-uncle along with letters, records and the telegram that told the family of his death.

Her great-uncle initially served with the 14th Battalion Argyll and Sutherland Highlanders before he was moved to the 1/7th Battalion Black Watch.

He was taken to a casualty clearing station on April 23 to get treatment for an injury to his foot.

On the way, his group was again shelled and he suffered abdominal injuries, dying the following day.

Mrs Barr said: "If you read the history you get the immense feeling that people were just sent out there to be killed. It is very sad that soldiers died in huge numbers.

"And Arras had the highest death rate per day than any of the battles."

The Battle of Arras, which lasted from April 9 to May 16, had an average daily death toll of 4076.

The service the moderator is taking part in - one of five official centenary events this year - will take place at the Faubourg d'Amiens Commonwealth War Graves cemetery in Arras on Sunday morning.