The cannier politician puts their case on the shop floor

During the election campaign of 2017, Tory strategists made many mistakes. In their defence, however, they took one decision that was both wise and extremely popular.

They kept Theresa May as far away as possible from the voting public. In an election campaign, there are few bigger risks a political leader can take than to pass within 50 feet of an actual voter. Just look what happened yesterday.

Jeremy Corbyn was campaigning in Glasgow. In a bid to impress the locals, he’d put on a tartan scarf. “I thought you’d be wearing an Islamic jihadist scarf!” bellowed a passer-by.

Inspecting the floods in South Yorkshire, meanwhile, Boris Johnson found himself repeatedly berated by locals for not having visited sooner. In fairness, he’d visited the floods in Derbyshire a couple of days earlier, and had even mucked in with a mop.

Unfortunately, while meeting voters represents a grievous political hazard, it’s generally frowned on to spend the entire six weeks of a campaign hiding from them in a cupboard, which is why the cannier politician adopts the following strategy: simply meet the voters in their place of work. As the voters will be under the watchful eye of their bosses, they’ll all be on their best behaviour, and you can drone away at them to your heart’s content without fear of being jeered, booed, or accused of supporting Isil.

David Cameron spent practically the whole of his 2015 campaign giving blissfully uneventful speeches in offices and factories, and yesterday afternoon, having recovered from his experience in South Yorkshire, Mr Johnson gave a speech at a car plant in Coventry. Now, this was more like it. Everyone sat up straight, listened and clapped politely as the Prime Minister ran through his latest gags about his Brexit deal (“It’s ready to go! Just add water! Stir in pot!”) and alerted factory staff to the threat posed by Mr Corbyn and his brand of “Bolivarian revolutionary socialism”.

Mysteriously, his speech did not contain the more personal attack on Mr Corbyn that had been briefed the night before by the Tory press office. Mr Johnson was planning to call the Labour leader a political “onanist”.

In the event, however, no such word left his lips. Asked to explain, Mr Johnson turned a light shade of pink, smirked furtively, and murmured that “a stray early draft” must have “found its way” into the newspapers via “a process I don’t pretend to understand”.

Still, credit where it’s due. It’s not often a politician gets a laugh for a joke he hasn’t actually told.