Hello King Ranger,
Thanks for your kind offer of taking a photo of the plaque but I have one already that I found on a Website recently.
Since I discovered Alexander Dunn died in Larbert Asylum I've found he was only in the place about 11 months. He died on the 9th Nov 1927 so is probably in Old Kilpatrick cemetery. His wife Martha nee McCallum was still living at old Church Place when he died.
It looks like our family story about him dying of wounds after WW1 is unlikely as he died 9 years after the war in 1927. Thank you all for your help.
If you see a Martha Dunn grave I'd be interested to know about it. I wonder if they had family?