From this story in the Scotsman:
A unique triple-barrelled shotgun made for a Scots aristocrat has been sold at auction for £43,000. The shotgun - dubbed the "Holy Grail" - was made in April 1891 for John Adrian Louis Hope, 1st Marquess of Linlithgow and the seventh Earl of Hopetoun. The three-barrelled ejector, 16-bore gun, with three triggers, was designed by renowned Edinburgh gun makers John Dickson & Son and is the only one of its kind. Its origins were identified after the gun was taken to a valuing event at Hopetoun House, South Queensferry, and it has now been sold at Holt's auction in London, to a private collector, after fierce bidding from around the world.
_Holt's founder, Nicholas Holt, said: "This is completely unique - the holy grail for any shotgun collector. "The gun maker, which still exists in Edinburgh, looked back in their records and found this was the only single 16-bore, round action side by side by side ejector ever made. The mechanism was too complex to make more, but it still works fantastically well today and is capable of shooting three gamebirds with its three barrels."