The “discovery” is in fact nothing of the kind. The painting in Woburn Abbey is included in every single catalogue I know of the paintings of Rembrandt, from John Smith in 1836 to Leonard Slatkes in 1992. Only one colleague, Christian Tümpel, ever assigned it to a pupil of Rembrandt’s rather than the master. When the painting was exhibited in 1950 in Edinburgh, Jan van Gelder, one of the greatest art historians and connoisseurs of the 20th century, wrote this about it: “... always wrongly placed within the chronology of Rembrandt’s work is the portrait of an Old Jew. After cleaning we find it signed and dated 1643, not 1633 (see Bredius 185). There can be no doubt about its authenticity.” (J.G. van Gelder, “The Rembrandt exhibition at Edinburgh,” The Burlington Magazine, vol. 92, nr. 572, November 1950, p. 328.) Although this may be phrased a bit defensively, I know of no printed record of doubt concerning the authenticity of the painting.