New York Times --
2 Irish Billionaires Clash Over Publisher’s Course
in which it is said of Tony O'Reilly--
He moved from rugby to dairy in the early 1960s when he became chief executive of the Irish Dairy Board, a co-operative of Irish farms, and then joined H.J. Heinz to become the first nonfamily member to run the business.
Well he did "join" H.J. Heinz in a package deal, as economic historian Cormac O'Grada politely explains --
Erin Foods ... specialise in lines such as packaged soup and processed vegetables ... [Mickey Joe] Costello resigned in 1966 and his successor, the youthful Tony O'Reilly set up a trading partnership with the H.J. Heinz Co. in 1967.
So Tony did a deal in which Heinz got access to Erin Foods' advanced food processing techniques, developed at taxpayer expense -- and then jumped over to Heinz himself.
Later on, the NYT explains the feud with Denis O'Brien --
The bad blood between the two began when Mr. O’Reilly, the former chief executive of Heinz, beat Mr. O’Brien in a battle for control of Irish telecommunications company Eircom Group in 2001. Mr. O’Brien did not take it lightly that someone who had joined the bidding contest after him and had less experience in telecommunications beat him to the punch.
No. The bad blood dates to when O'Reilly was in one of the losing consortia for the bid on Ireland's second mobile telephone licence, won by O'Brien. There is an O'Reilly grudge going back to that award and the non-Fianna Fail government which oversaw it -- a grudge that has had a major impact on Irish politics since then with his newspapers in effect campaigning against the 1994-97 coalition and doing major ball carrying duty for Taoiseach Bertie Ahern regarding his own much investigated but poorly understood financial dealings.
Incidentally, in that 2003 Eircom deal that O'Reilly won, the Irish public got fleeced.
The trouble with disputes between rich people is that you might have to pick one of them to cheer for. It's a clear choice in this case.