Mr Wellby, whose jewellery collection was sold by Sotheby's in a white glove sale in December (see next week'sJewellerycolumn), came from a London family of silversmiths and dealers.
Opening his own shop in the 1960s, he became an acknowledged expert on northern European Renaissance and baroque silver.
Tim Wilson, the Ashmolean's Keeper of the Department of Western Art, who was a close friend of Wellby, described the gift of 16th and 17th century items as "the most important accession of objects of this sort to any UK museum since the bequest of objects from Waddesdon Manor by Ferdinand Rothschild to the British Museum in 1898".
Many of the pieces he kept for his personal collection were acquired in the mid 20th century when the ornate style of German silver was regarded as old fashioned.
"In the manner of the grand old dealers, he could be quite cagey about where he actually acquired things," Mr Wilson said. "There was nothing underhand about it, most were bought at public auctions on the continent, but he liked to play his cards very close to his chest."
A selection of some of the most spectacular pieces will go on show in a temporary display next month before the entire collection is displayed in a permanent gallery.