Information kindly shared by Peter Newling:
Richard Charles Dundas Firth is commemorated on the Dundonnell memorial and buried at Bordbuie Burial ground, Dundonnell. On the gate of this remote burial ground is a Commonwealth War Graves sign.
He was a Lieutenant in the 9th Battalion, South Lancashire Regiment and he died at Eastbourne in December 1914. I don't know the cause, whether illness or accident. His unit had not been overseas - it was newly formed and had just started training.
The Firths were a prominent Sheffield family - a previous generation had developed a process in the making of stainless steel. I think [but am not sure] that Richard Firth was at Dundonnell House [or possibly Eilean Darach if it was a separate estate then] as a tenant before the war. "Miss Firth" features in a story which is told of soldiers on leave from the war poaching - Richard's sister, I presume.