Because Mitchell's Merseyside-born father's family were from Scotland and his mother is Welsh, Mitchell considers himself British rather than English. He explored his ancestry in an episode of the television programme "Who Do You Think You Are?", discovering his connection to the Gaelic scholars John Forbes and Alexander Robert Forbes. On 7 August 2014, Mitchell was one of 200 public figures who were signatories to a letter to "The Guardian" expressing their hope that Scotland would vote to remain part of the United Kingdom in September's referendum on that issue. Mitchell's participation in the open letter follows a May 2011 "The Observer" column, in which he concludes that "If Scotland ever goes it alone ... the British will have lost their country".