A treasure trove of objects found hidden in the attics and cellars of a Highland castle will go on sale at an auction next month.

Paintings and sculptures, crested dinner services, silverware and an array of objects from the kitchen at Dunrobin Castle are among the items that will go under the hammer.

They were found during a “decluttering” of attics and cellars at Dunrobin Castle near Golspie in Sutherland.

Estimates for items in the sale range from £80-120 for a collection of pewter sugar moulds, £8,000-12,000 for a portrait of the Duke of Brunswick by the Dutch golden age portraitist Jan van Ravesteyn, and £8,000-10,000 for a pair of 18th century Scottish all-metal flintlock belt pistols made by Alexander Campbell of Doune.

Charlie Thomas, director of house sales at Bonhams, said: “The Dunrobin attic sale provides a glorious opportunity to purchase a piece of history from one of Scotland’s grandest and most historic castles.

“Many of the items have been hidden away in Dunrobin Castle for generations and never been seen on the open market before.

“They provide a wonderful snapshot of what it was like to live both upstairs – and downstairs – in the Highlands’ premier ducal palace.”

Other items found during the decluttering include vintage ski equipment, 19th century lanterns and Victorian plaster busts discovered in the cellar.

The Dunrobin attic sale will take place at Bonhams on Queen Street, Edinburgh, on Tuesday April 20.

Dunrobin Castle is the family seat of the 25th Earl of Sutherland and has been home to the earls and dukes of Sutherland since the 13th century.

Charles Graham-Campbell, managing director of Bonhams in Scotland, said: “Attic sales are always very popular and the Dunrobin attic sale has everything – great provenance, fascinating items and of course a rare glimpse into a way of life now long vanished.

“I am sure that many members of clan Sutherland around the world and indeed expatriate Scots everywhere will be eager to take part in the sale.

“We are very much looking forward to what promises to be the highlight of our spring season.”