A unique painting of the Battle of the Boyne is being restored in a castle because it is too big to move off-site.

Pearl O'Sullivan uses a swab during the conservation of Jan Wyck's painting,The Battle of the Boyne at  Malahide Castle in Dublin.

Pearl O’Sullivan uses a swab during the conservation of Jan Wyck’s painting,The Battle of the Boyne at Malahide Castle in Dublin. Image by Niall Carson/PA Wire

Dutch painter Jan Wyck’s panoramic record of the largest battle ever fought on Irish soil was completed just three years after the 1690 clash between Protestant King William III and Catholic King James II.

Measuring more than three metres long and over two metres high, the impressive canvas has been hanging over the dining room of Malahide Castle, in north county Dublin, for the past 40 years.

Fourteen members of the Talbot family, who built the castle, died at the battle fighting for the Jacobites.

The painting was bequeathed to the National Gallery in 1936 and has been on loan to Malahide since 1976.

Pearl O'Sullivan uses a swab during the conservation of Jan Wyck's painting,The Battle of the Boyne at  Malahide Castle.

Pearl O’Sullivan uses a swab during the conservation of Jan Wyck’s painting,The Battle of the Boyne at Malahide Castle. Image by Niall Carson/PA Wire

Its sheer size – reflecting the epic scale of the bloody milestone in Irish and British history – has forced the National Gallery of Ireland, which owns the painting, to restore it on site.

Sean Rainbird, director of the gallery, said it needed renovation for a landmark exhibition of Irish history next year, as part of the Decade of Centenaries commemorations.

“Following completion of the project, the painting will return to the gallery for a period and will be one of the key works in our 2016 exhibition, Creating History: Stories of Ireland in Art, before retaking its place in the historically significant surroundings of Malahide Castle, where it has been on show for many years,” he said.

Once restored, experts will have to remove the painting from its frame, and roll it up to get it out of the castle doors for its temporary move to the National Gallery.

Wyck’s vision captures the chaos and carnage of the battle at Oldbridge, in Co Meath.

With the help of funding by the William E Connor Foundation, two conservation experts are working full-time to painstakingly restore the centuries old painting in situ at Malahide Castle.

Visitors can catch a glimpse of the work as they pass by.

Wyck painted a number of versions of the Battle of the Boyne – smaller versions are in the collections of the Ulster Museum and the National Army Museum, London.

(Press Association)