LONDON — In the 1970s, the British comedian Tommy Cooper used to tell a joke about asking an auction house to value a violin and a painting that he had discovered in an attic. The good news, he was told, is that they were made by Stradivarius and Rembrandt. The bad news was that the painting was by Stradivarius and the violin was by Rembrandt.

He then proceeded to ram the violin through the canvas.

In those days, of course, Rembrandt was the gold standard. But the Dutchman and his fellow old masters have fallen out of fashion and are no longer as coveted by collectors and investors.

As a measure of that fall, 10 works have sold at auction for more than $100 million since 2004, and all of them were made by modern or contemporary artists in the past 120 years. Older paintings have seen their value, in relative terms, level off or decline. The trend was plain to see in recent weeks, as London’s auction houses tried to find buyers for their latest tranche of old masters. As has been the case in recent years, there were few works by major names.

Christie’s biannual evening sale on Dec. 8 raised just 6.5 million pounds with fees, about $9.7 million, against a low estimate of £12.7 million. Nineteen of the 45 works, or 42 percent, failed to sell, including the two most highly valued lots — a 1582 watercolor study of a hare among plants by Hans Hoffmann, a pupil of Albrecht Dürer, and a fine 1770s Francesco Guardi view of the island of San Giorgio Maggiore in Venice, carrying low estimates of £4 million and £1.5 million respectively.