There are many reshuffles that provoke surprise; there are some that prompt bemusement as well. Rishi Sunak’s decision to install David Cameron as the seventh foreign secretary in seven years is one that does both. The former prime minister will bring undoubted strengths into the top team and to the UK’s relationships abroad. The concern must be, however, that these could be outweighed by the controversial legacy he brings too. And none of that says that he can bring back voters for his party at home.