Hi Dermo!
I am not very familiar with other areas of Dublin, as I only visited there for about a week, visiting relatives. My great-great grandparents are John O'Brien (1818-1894) and Mary Lowry (-1896). Their children were William b. 1847, Mary b. 1849, Patrick b. 1851, Margaret, John b. 1853, George (1855-1937) and James (1856-1926). Who was your Howth Grand-uncle?
Lynn