“I’ve reluctantly discarded the notion of my continuing to manage the portfolio after my death – abandoning my hope to give new meaning to the term ‘thinking outside the box’.”

In his annual letter to shareholders on Friday, ­Warren Buffett resorted to customary self-deprecating humour to tackle two thorny issues: his mortality and the future of Berkshire Hathaway, the $220bn conglomerate he has assembled during 43 years of savvy investing.