Saudi Arabia’s crown prince, Mohammed bin Salman, came to Downing Street on Wednesday, having had lunch with the queen. Yesterday evening he dined at Chequers. A petition against his visit, just passing the 10,000 signatures at which the government must respond, elicited a statement assuring the public that British values would be stressed during the visit, and that UK arms export licences were subject to the highest standards of scrutiny concerning their eventual targeting. There are guests at Yemeni funerals who would no doubt beg to differ.