One of the finest self-portraits of Sir Anthony Van Dyck (1599-1641) has to raise £12.5m ($20m) in order to remain in the UK.
The work is one of the most intimate created while Van Dyck - one of the finest portrait artists to have lived - was based in the UK, and has been placed under a temporary export bar based on its strong connection with national history.
Culture Minister Ed Vaizey said: "We have recently had a number of successes in preventing national treasures from being permanently exported from the UK thanks to the generosity of donors and the fundraising efforts of our museums and galleries.
"I hope that placing a temporary export bar on this magnificent painting will allow time for a UK buyer to come forward and ensure it remains here in the UK."
The painting was originally sold at auction for £15.1m ($24.6m) through Sotheby's in 2009, setting a record for Van Dyck's work, but is believed that have been sold again since, according to the Guardian newspaper.
Any interested buyers have until February 13, 2014 to raise the sum, though if serious intentions are shown, the date may be extended until July 13, 2014.
Also placed under an export bar is a cast of Napoleon's death mask, which was recently sold at auction for £175,100 ($280,640). Vaizey cites the 200th anniversary of the Battle of Waterloo in 2015 as the reason that the mask should stay in the UK, adding:
"This is perhaps one of the most unusual objects I've ever come across, both fascinating and somewhat macabre, but I believe it should remain here, and hope a UK buyer steps forward to help ensure that happens."
Take a look at this Napoleon Bonaparte autographed letter we currently have in stock.
Buyers have until January 12, 2014 to raise more than the auction bid.
These aren't the first items to have come under an export bar, with a ring belonging to author Jane Austen prevented from leaving the UK recently, after the sum was raised by the Jane Austen House Museum.
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