mayor
... that Bristol was the only one of the ten cities in England and Wales to have mayoral referendums on 3 May 2012 which voted to switch to a directly elected mayor?
... that <a href="./Bristol" id="mwB74" rel="mw:WikiLink" title="Bristol">Bristol</a> was the only one of the <a class="mw-redirect" href="./English_mayoral_referendums,_2012" id="mwB78" rel="mw:WikiLink" title="English mayoral referendums, 2012">ten cities in England and Wales</a> to have mayoral referendums on <span about="#mwt27" class="nowrap" data-mw='{"parts":[{"template":{"target":{"wt":"nowrap","href":"./Template:Nowrap"},"params":{"1":{"wt":"3 May"}},"i":0}}]}' id="mwB8A" typeof="mw:Transclusion">3 May</span> 2012 which voted to switch to a directly elected <b id="mwB8E"><a href="./Mayor_of_Bristol" id="mwB8I" rel="mw:WikiLink" title="Mayor of Bristol">mayor</a></b>?