In late October, Bonhams announced that a painting found in the cupboard of an Oxfordshire house was actually a forgotten portrait by Spanish artist Diego Velázquez. The masterpiece, which had been consigned for sale together with a number of works by 19th-century British artist Matthew Shepperson, is now going to be the highlight of Bonhams’ Old Master Paintings auction, which takes place today (December 7), and is expected to fetch something in the region of £2 million to £3 million.

The news comes hot on the heels of another thrilling discovery, a painting unearthed in the attic of a house in Northamptonshire last spring, which could be an early Cézanne, and, if this is proven, worth up to £40 million. Charlie Wells from Prime Purchase in the Cotswolds has come across many other treasures that would have been lost if an experienced eye hadn’t been cast over them, and
says that ‘chattel experts sleep uneasily in the autumn, wondering how many thousands of pounds may have been innocently added to bonfires’. He believes most people are aware of the value attached to paintings that have always hung on walls or furniture on display, but items stuffed into the attic or outbuildings catch them out.

Few vendors sell a house without having a valuation, and Mr Wells recommends doing the same for its contents. Getting specialist advice to determine the worth of furniture or artworks is crucial, agrees Quintessentially Art’s managing director, Gary Krimershmoys. A scientific examination might be required to assess whether a work is genuine-the unknown Velázquez was extensively analysed by some of the foremost experts on the painter-and you’ll also need to verify the provenance to make sure the work hasn’t been stolen. And if the piece is of some value, you should have it properly restored before calling the auction house.

At the very least, vendors planning to sell some contents together with their country house should discuss with the buyer exactly what’s included in the sale, advises Fiona Graham, a partner at law firm Boodle Hatfield in Oxford. ‘If the seller is nervous that a Monet could be discovered in the attic after the sale, he can insert a clause into the contract that if anything worth more than a certain amount is found, the item belongs to him, although this may be hard to enforce.’

Mrs Graham also advises caution when it comes to the hazy area of fixtures and fittings. Where sellers try to remove a panel or plaster with a work that’s been painted on it, a buyer could argue it’s a fixture as it’s part of the house (rather than a fitting that can be taken away). This is especially true of statues, about which there has been much legal debate: ‘If they can be linked to the house, they might be regarded as fixtures.’

Property finder Adrian Wright from Private Property Search recalls a house that he helped purchase for a client, which had a Lucien Freud work painted directly onto a wall. ‘The vendor wanted to move it and reduce the price accordingly, which suited my client. My advice would be to check if a painting is part of a property’s listing, which means the vendor can’t remove it. Assuming you can legally remove and sell your contents, this may help prevent an unwanted property sale.’

Charles Smith of Sotheby’s International Realty remembers a widowed client who was reluctantly going to put his house up for sale. ‘A visit from Sotheby’s confirmed the furniture was worth hundreds of thousands, and selling it meant the property no longer needed to go on the market,’ he explains.

However, you do need to be aware of trends, adds Mr Smith. ‘Furniture and art from the 1950s and 1960s are particularly collectable now, whereas dark Victorian furniture isn’t very popular, and therefore not as valuable.’

Art and tax facts

  • Valuable art that can benefit the nation can be held for a gallery or museum in lieu of Inheritance Tax or Capital Gains Tax on your death
  • Don’t forget old maps, estate plans and other historical documents that could be of interest to The National Archives in lieu of taxes

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