This week, Mohammad bin Salman, also known as MBS, is on his not-quite-state visit to Britain. A parade down the Mall and a state banquet could only be afforded to his father, old King Salman, who made MBS crown prince last June and has given him unprecedented latitude to liberalise Saudi society, lock up his enemies and light fireworks abroad. MBS arrived in London on Wednesday fresh from visiting one friend, Egypt’s General Sisi, and will go on to see another, Donald Trump, on 19 March. Theresa May’s aim will be to show that Britain can thrive outside the EU, but she should think twice before co-opting this new strongman who reputedly encourages his courtiers to call him Iskander — the name by which Middle Easterners know Alexander the Great.