Four days before his stunning electoral comeback, Luiz Inácio Lula da Silva , Brazil’s president, got his first smartphone.

Lula, who turned 81 last Tuesday, had long said he wanted to avoid an endless stream of calls during his rare moments off, and he began his presidential campaign by sticking to an old habit: using aides’ phones – only when necessary.

Then he suffered an unexpected first-round defeat to the far-right senator Flávio Bolsonaro, who had neither his father Jair Bolsonaro’s charisma nor much of a record as a two–decade legislator – and Lula realised he had lost both in the ballot box and in the digital arena.

The veteran leftist, who contested his first election more than 40 years ago, overhauled his digital strategy, began recording selfie-style videos – and went on to beat Bolsonaro by more than 4.4m votes.

There are many explanations for how he managed to boost turnout and win over other candidates’ voters.…