"Closer examination reveals not only the fine quality of the varnish, but also that it was made on Stradivari's 'forma B piccola' (with the soundholes placed differently) and that its maker was Carlo Bergonzi, with the help of his son, Michel Angelo. . .The cello's history must surely be that it remained unused during the second half of the 18th century before being enlarged in Madrid, most likely by Silverio Ortega. . . . Hills understandably disagreed with the Stradivari attribution and declined to buy the instrument. . ."
Carlo Bergonzi: A Cremonese Master Unveiled, Christopher Reuning, editor, Consorzio Liutai Antonio Stradivari, Cremona, 2010