As a collection field, philately appeared after the introduction of the postage stamps in 1840, but did not gain large attraction until the mid-1850s. Some authors believe that the first philatelist appeared on the day of the release of the world's first postage stamp, dated to 6 May 1840, when the Liverson, Denby and Lavie London law office sent a letter to Scotland franked with ten uncut Penny Blacks, stamped with the postmark "LS.6MY6. 1840." In 1992 at an auction in Zurich, this envelope was sold for 690 thousand francs.