A 77-year-old academic who died in 2006, has left two Pre-Raphaelite masterpieces worth millions of pounds to Oxford's Ashmolean Museum.
The oil painting by Sir Edward Coley Burne-Jones entitled "Music"
The treasure trove was discovered during a valuation on Jean Preston's Oxfordshire home said auctioneers Dukes of Dorchester.
The paintings are by Sir Edward Coley Burne-Jones and Dante Gabriel Rossetti.
The state accepted them "in lieu" of inheritance tax. Other paintings found in home in 2007 fetched £2m.
Guy Schwinge, of Duke's of Dorchester, said: "The late owner was a great supporter of the Ashmolean and it was her express wish that these magnificent pictures should further enhance their outstanding collection of Pre-Raphaelite paintings".
Hamlet and Ophelia
The oil painting by Sir Edward Coley Burne-Jones, entitled "Music", was commissioned by the artist's most important patron, William Graham, and was sold at Christie's Auctioneers on the 13 April 1934 for £147.
It was at this time that the painting entered the collection of Kerrison Preston of Bournemouth.
The watercolour by Dante Gabriel Rossetti depicting Hamlet and Ophelia, is monogrammed and dated 1866.
It was commissioned by A.T. Squarey, a Merseyside lawyer and art collector.
The lost renaissance panels, which were auctioned for £2m, were discovered hanging behind the door of Mrs Preston's bedroom last year by former Bristol University art history expert, Michael Liversidge.
The altar panels - which carry portraits of two saints - painted by Italian monk Fra Angelico in 1438, disappeared after the altar they adorned was destroyed in the Napoleonic wars.
Mr Liversidge said Miss Preston had been working as a curator of historic manuscripts at a museum in California when she bought the two paintings for about £200 in the 1960s.