An E-ELT case study: colour–magnitude diagrams of an old galaxy in the Virgo cluster A. Deep, G. Fiorentino, E. Tolstoy, E. Diolaiti, M. Bellazzini, P. Ciliegi, R. I. Davies and J.-M. Conan A&A, 531 (2011) A151 Published online: 05 July 2011 DOI: 10.1051/0004-6361/201116603