An interesting point about the image in the Illustrated London News article is that it showed the Lycurgus Cup with a foot which, as stated in Harold Newman's An Illustrated Dictionary of Glass, 1977 was "an attached modern metal base" and was removed after purchase by the The British Museum in 1958.
Newman also made reference to: "Recent analysis of the glass shows traces of silver and other metals, which may contribute to the dichroic effect." He also included an information source reference to Journal of Glass Studies (Corning) V (1963).