Slane Castle owner Lord Henry Mount Charles has passed away at the age of 74 following a battle with cancer.

In a statement, Lord Henry's family said he died peacefully late last (18 June) and that "his courage and unwavering spirit inspired all who knew him."

They said the 74-year-old leaves behind "an extraordinary legacy as a passionate steward of Ireland’s heritage, dedicating his life to preserving Slane Castle and transforming it into a beacon of culture, music, and community.

"His visionary leadership and generosity touched countless lives, while his warmth, humour, and resilience endeared him to friends, colleagues, and admirers across generations."

The family expressed their gratitude to the staff at St James's Hospital in Dublin, where Lord Henry received treatment over the past decade and requested privacy as they grieve their loss.

"Lord Henry’s light will continue to shine through the lives he enriched and the enduring contributions he made to Ireland’s cultural landscape. He will be profoundly missed, but never forgotten."

Part of the Anglo-Irish aristocratic family and formerly styled as Viscount Slane, Lord Henry first opened up Slane Castle for concerts in 1981.

Over the past four decades, the natural amphitheatre at Slane has hosted some of the world's biggest rock and pop acts before crowds of 80,000.

The 1,500-acre estate is also available for weddings, corporate events, private dining, festivals, and is due to host reality show The Traitors Ireland for RTÉ.

Acts including U2, Queen, The Rolling Stones, Madonna, Guns N' Roses, Metallica, Red Hot Chilli Peppers, David Bowie, Bob Dylan, Bruce Springsteen, REM, Robbie Williams and Oasis have performed in the grounds of the stately home in Meath.

Harry Styles was the last artist to headline Slane in 2023, with Lord Henry's son, Alex Conyngham, Earl of Mountcharles, having spoken about the venue's struggle to book performers.

He cited competition from the 3Arena and Croke Park, where artists can perform over multiple nights, although he is confident of Slane returning in 2026.

Slane Castle Ltd reported a deficit of €226,400 at the end of 2023, the last year for which accounts are available.

The company stated fixed assets of €980,500 and current assets of €68,100, including just under €20,000 in cash, against current liabilities of €509,400 and long-term liabilities of €765,700.

The company, which employs around 15 people, listed the value of a premises refit at €578,400 and a trail project at €163,100, with €138,700 in fixtures, fittings and equipment among its tangible assets.

Slane Castle Ltd was wholly owned by Lord Henry until last July, when Isle of Man-based RAP Investments Ltd was granted equity, and the €667,500 owed to RAP being listed as inter-company loans.

The accounts also list a €173,100 balance owed to Lord Henry and his wife, Iona Mount Charles, and €71,800 owed to credit institutions among the company's creditors.

Of the €837,400 listed in formal loans, €71,800 was owed last year, €41,300 was due in one to two years, €55,400 in two to five years, and €669,000 in five years or more.

"The shareholder loans amounting to €667,480 comprise two loans from a shareholder which were repayable on demand," a note in the accounts reads.

"It was agreed to capitalise these loans and this occurred on 22 July 2024. As the loans were capitalised it is deemed appropriate to retain the loans as long term at the 31.12.2023."

The accounts also show that Slane Castle received €27,000 from the Department of Tourism, Culture, Arts, Gaeltacht, Sport and Media in 2021-22 to upgrade its website.

Slane received a further €15,200 from the Local Enterprise Office as part of the Feasibility Study grant programme "to assist activity providers to withstand the challenges of the tourism sector"

The company also received a total of €138,800 from Meath County Council to restore St Eric's Hermitage in the grounds of Slane Castle (€112,400) and for the "conservation of archaeological heritage" (€26,400).

Slane Castle Ltd recorded a profit of €66,700 in 2023, more than triple the €19,700 it made in 2022.

Lord Henry and Alex Conyngham also founded Slane Castle Irish Whiskey before selling it to Jack Daniels maker Brown Forman in 2017.

The company made a loss of €3.2m in the 12 months to 2023, although the value of its whiskey stocks rose to €29.2m and total assets of €45.6m, with reserves of €67.4m.

Brown Forman invested €50m to turn Slane Castle's outer courtyard into a whiskey distillery, and the company is still run by the Conyngham family.

Alex Conyngham described the deal to The Spirits Business as "technically an acquisition" but "more of a partnership because the family is still very involved."

According to Forbes, the distillery produces 500,000 bottles of whiskey a year and has the capacity to scale annual production to 1.2m bottles.

Photo: Lord Henry Mount Charles. (Pic: RTÉ)