As part of the assurance, Bureau Veritas undertook: interviews with relevant personnel of WPP responsible for GHG emissions accounting; a review of WPP data and information systems and methodology for collection, aggregation, and analysis; a review of information and calculations used to determine GHG emissions; sampling of source data from audit visits to two of WPP’s UK locations: JWT London and TNS UK Limited, and to the WPP Head Of!ce in London to review underlying systems and emissions data; and a review of the consolidated 2012 data to check end of year accounting and reliable transposition.