Mary Haughey and her daughter and sons own health and veterinary products firm Norbrook Laboratories, which was founded in 1969 by her Louth-born late husband Edward, who held the title of Lord Ballyedmond, and who died in a helicopter crash in 2014. Â£104m (€117m) of assets including properties and farmland were transferred to Mary and her family in 2015. It was reported that her husband left an estate worth Â£472m (€530m) in total.
The privately-owned firm, which is now run by former Sisk chief Liam Nagle and employs over 2,000 staff around the world, filed its latest accounts showing sales of Â£272m (€306m) in 2017. It booked a profit of Â£39.4m, and there was Â£128m in shareholders' funds.
Other assets include a property in London's Belgrave Square worth tens of millions alone, as well as others homes, castles and estates in Dublin, Norfolk, Northern Ireland, Carlisle, Co Louth and Uganda.