Laconian pottery in Madrid

I note that the Laconian cup attributed to the Hunt painter (though there is some disagreement) and formerly in the  Várez Fisa collection (Madrid inv. 1999/99/45) appears to be the same as the one sold at Christie's London 13 December 1995, lot 224, for £34,500 ($52,871). (Christos Tsirogiannis has come to the same conclusion.) The cup is listed as "The property of a private collector".

The tondo decorated with a komast scene, a standing figure playing the double pipes whilst two dancers dance energetically, a bird in the field, with two birds on either side of a columned altar in the field below, with radiate design on the underside.
4¾in. (12cm.) high; 8¼in. (21cm.) diam. excl. handles.

Who consigned the cup to Christie's? What was its collecting history prior to 1995? Who was the anonymous private collector?

• Cabrera Bonet, P. Editor. 2003. La colección Várez Fisa en el Museo Arqueológico Nacional. Madrid: Ministerio de Educación, Cultura y Deporte. No. 46.
• Warden, P. G. Editor. 2004. Greek vase painting: form, figure, and narrative. Treasures of The National Archaeological Museum in Madrid. Dallas: Southern Methodist University Press. No. 11