Collecting histories and the Chesterman collection

Now that Bonhams has withdrawn an Etruscan antefix from its auction due to what appear to be links with the Medici Dossier it is important that the collecting histories of the Chesterman collection of terracottas are explored and investigated.

Are any of the sources for these terracottas ones that are already known from the hundreds of objects already returned to Greece and Italy?