According to writer and actor Mark Gatiss, his whole career has been “a long revenge against PE”. Children who aren’t sporty, he adds, can “take heart” from his success, which is partly rooted in his talking about horror movies with his best friend when he should have been running around on the sports field.


It’s perhaps not surprising that Gatiss the storyteller, a man central to reimagining Sherlock Holmes for the modern age, is someone who finds “romantic connotations” in his late mother Winnie’s Irish ancestry. He would, he jokes at the start of his episode of Who Do You Think You Are?, quite like to discover he’s “the King of Ireland”.

Mark heads for Belfast, where his grandfather, Jeremiah O’Kane, trained in medicine at Queen’s University. Among the documents Mark sees is an obituary of Jeremiah’s mother, Margaret. This suggests she was the daughter of a landowner, Jeremiah O’Mullan.

Land valuation records confirm this story. In the 1880s, Jeremiah O’Mullan owned more than 700 acres. Mark sees a picture of his 2x great grandfather as a young man. (“Look at that nose, it’s been following me for centuries.”) Jeremiah was a Catholic, thus unusual at a time when most landowners were Protestants. Earlier documents deepen the mystery. Jeremiah’s father, George, was a tenant farmer. How did his son come to be so wealthy?

To understand more about George’s life, Mark heads for rural County Londonderry and “bleak, barren, cold” country. He sees an area once largely controlled by the Worshipful Company of Fishmongers, after the Crown granted land to the guild as part of 17th century efforts to colonise the area with Protestants.

George worked for the Fishmongers as a land steward and herdsman, the 19th century equivalent of a farm manager. This put him in a difficult position because locals resented the guild’s ownership of the best cattle-grazing land, and George faced intimidation from his neighbours.

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Mark also sees a reference to George in the work of John O’Donovan (1806-61), who travelled in the area through his work with the Ordnance Survey. George told O’Donovan a family tale of murder. Mark is delighted to find a storyteller among his ancestors – and even more delighted to find George’s tale may have links to a famous Irish vampire story.

But Mark has yet to find is evidence of how Jeremiah O’Mullan got his money. Things only get more perplexing when Mark sees documents suggesting George hit financial problems around the time of the Great Famine. Of George’s five sons, four left Ireland, part of a mass emigration during this era.

Bernard O’Mullan did well for himself in New South Wales and left a fortune equivalent to around £400,000 today. Jeremiah inherited some of this money and bought land, including the family homestead of Ashlamaduff. It’s still owned by one of Mark’s relatives, Betty-Ann, who’s able to take Mark to his ancestral home.

“This whole situation is like a Western, I think,” says Mark. “The grazing of the cattle, the pushing out of the indigenous people onto poor land, it’s really interesting – and this is a bit like a Native American getting a little bit of Manhattan back.” He’s going to write an Irish-set ‘Western’ based on what he’s found, he adds, ever the storyteller.


As for the idea of being King of Ireland, it seems extended Irish families once had their own chieftains known as kings. Perhaps Mark really is descended from rural royalty.