Tax is one. His nemesis, Maurice Levy, is another. So, fingers crossed Sir Martin skipped reading the Financial Times last Tuesday. In it, his French frenemy penned a piece titled "I am not a masochist, but the rich must pay more", wherein the Publicis chairman offers to pay more tax to do his bit to stem economic decline. Perverse, non? Until you realise how much such a sentiment would enervate the WPP boss, who, after three years in Dublin, is only now considering moving shop back to the UK thanks to some major tax-cutting by George Osborne. In riposte, Diary imagines the diminutive knight will show no merci.
If you happen to be in conversation with Sir Martin Sorrell, there are a couple of subjects to avoid.