Is Celtic manager a distant cousin of Robert the Bruce?

New research has discovered that the O’Neill family from Northern Ireland were closely related to Bruce, who led Scottish forces to victory over the English at the Battle of Bannockburn in 1314.

And some of the same character traits that made Bruce such a great leader may have been passed on to the Celtic boss, whose success in European competitions seven centuries later include victories over top English sides Blackburn and Liverpool.

The connection between Bruce and the royal O’Neills has been made through research by an American genealogist called Andrew MacEwen and is to appear in the fourth edition of Robert Bruce and the Community of the Realm of Scotland by Professor Geoffrey Barrow of Edinburgh University.

The link explains much about the Bruce family, including Edward Bruce’s brief spell as king of Ireland and vital aid given to Robert the Bruce by the Irish when he was a fugitive from English troops.

And Mr MacEwen, who runs an antiquarian bookshop called Victorian House Books in Stockton Springs, Maine, said modern-day O’Neills could well be related to Robert the Bruce, including Martin O’Neill.

"He’s probably one of those O’Neills, so there could well be a connection [to Bruce] through the O’Neills, if he could trace his ancestry back," said Mr MacEwen.

"You can find a lot of information on the O’Neills, it’s not that difficult. They are all supposedly descended from ‘Niall of the Nine Hostages’ in the fifth century."

Robert the Bruce’s grandfather, the Earl of Carrick, was called Niall, an unusual name in Scotland at the time, which has previously baffled historians as the traditional family tree gave no indication of an Irish connection.

But Mr MacEwen believes a generation was missed out from the lineage and Niall Bruce was the son of Nicholas Bruce and an O’Neill woman, and was named after his maternal grandfather, the Irish king Niall Roy.

Previously, Niall was thought to be the son of Duncan, whom he succeeded as earl, but Mr MacEwen has found records showing that Nicholas was Duncan’s son and heir. His theory is Nicholas died young or was killed in battle and he, along with his marriage to an O’Neill, was lost from the historical record because he never became the earl.

This explains several connections between Robert the Bruce and Ireland. His brother Edward is said to have been fostered by Niall Roy’s grandson - a story previously dismissed by some historians because there was not thought to be any relation between them.

And in The Remonstrance - a document declaring Ireland to be an independent country and similar to the Scots’ Declaration of Arbroath - Robert and Edward are both described as being descended from "our noble ancestors" by the Irish.

Professor Barrow said: "He has convinced me completely, and I hope it is right. Nobody has ever explained why an earl of Carrick was called Niall. It’s unique in the Scottish peerage of this time."

Adam Middleton, of Crucial Genetics, a company which specialises in DNA profiling and which is building up a database of the genes of the Scottish and Irish clans, said it would be possible to find out if Martin O’Neill was related to Bruce.

"You can analyse DNA from any two individuals and see if there’s a relationship there, but it would rely on having some DNA material from somebody directly descended from Robert the Bruce," he said.

A spokeswoman for Celtic FC said Mr O’Neill was unavailable for comment.