The collection of coins and medals belonging to the Duke of Northumberland were sold in a series of three auction sales by Sotheby's from 1980-1082. The sales included:
1-2. European Historical Medals from the Collection of His Grace the Duke of Northumberland. Sotheby's, London, Auctions December 1980 and June 1981.
3. Roman Coins from the Collection of His Grace the Duke of Northumberland K.G., P.C., G.C.V.O., F.R.S. Removed from Alnwick Castle. Sotheby's, London, Auction 4 November 1982. This sale included Roman Republican and Roman Imperial coins, in bronze, silver and gold. Many of the Roman Republican coins in the 1982 auction were described in Adm. William H. Smyth, Descriptive Catalogue of A Cabinet of Roman Family Coins (1856).