Wow that's fantastic - thanks to Shanew and Pastmagic, many obstinate pieces of the jigsaw now fit together!
So Elizabeth Ruddell, the future wife of Thomas Clarke was the daughter of William Ruddell's first wife Elizabeth Galbraith. And the Ruddells were probably methodist, perhaps from County Armagh. Elizabeth Ruddell married Thomas Clarke and their first child was christened Elizabeth Galbraith Clarke, born 1868. Their first son and second child was christened William Ruddell Clarke, born 1870.
One spelling correction to the Peerage.com entry, Elizabeth Ruddell married Thomas Clarke, not Clark. See Peerage.com Person Page 36573 for their descendants.
Pike's Contemporary Biographies of Cork 1911 has a good entry on Thomas Clarke.
So Elizabeth, Ruddell, a daughter of Dublin Snuff and tobacco manufacturer William Ruddell married Thomas Clarke son of Cork snuff and tobacco manufacturer, William Clarke! Is there any evidence that Clarke's Tobacco inocrporated Ruddell's? By a=way of footnote, Clarke's Tobacco (Wm Clarke and Son) was founded in Cork in 1830, was later headquartered in Dublin at Dolphins Barn, and then moved their headquarters to a new factory they built at Hare Place, Scotland Road, Liverpool in 1870. In 1901 they were one of 13 UK companies who amalgamated to form Imperial Tobacco to compete with the American Tobacco Company