Â© Licensed to London News Pictures. 08/12/2011, London, UK. Eric Clapton's signature inside the guitar. A Bonhams employee holds Martin 000-28 EC Eric Clapton signature model acoustic guitar which Clapton used recording his Change The World and Pilgrim Albums. . The guitar is expected to fetch 20,000-30,000 GBP.  Bonhams, London, photocall for entertainment memorabilia today, 8th December 2011. The auction takes place on Thursday 15th December.  Photo credit : Stephen Simpson/LNP