Don’t run through fields of wheat might be an obvious one, along with don’t propose untested policies in the middle of election on which you’ve gambled your and the nation’s futures.

However, the most important lesson anyone could learn from her premiership is that successful leadership means engaging with your audience, whether they are Members of Parliament or members of the public.

Any prime minister would have found it challenging to negotiate an exit agreement that satisfied the many competing desires of the different factions in the House of Commons. However, Theresa May made the process harder for herself by excluding all but a small core of loyal followers from the process until right at the end. She began her negotiation by announcing red lines that were as much of a surprise to MPs as they were to the EU. She made no attempt to explain her negotiating objectives beyond the much parodied “Brexit means Brexit”. The idea that revealing anything would weaken the UK’s hand became a point of principle for her, while attempting to extract any information at all out of the government became a game for opposition MPs.

May only began to engage with MPs, whose support she was always going to need for any agreement, when she had to sell her deal to them, and by then it was too late. No amount of last-minute compromise or sweeteners would ever be enough to win them over. Even when, after months of difficult contortions, May offered up her own metaphorical head on a platter to her political enemies, like a strange confusion of Salome and John the Baptist, it wasn’t enough.

It isn’t just Boris Johnson who can learn from his predecessor's strategic failure. When it comes to big changes or major programs, most organisations in the public, private and charitable sectors make the same mistakes. Whether it’s a multinational company restructuring or a charity explaining a new policy to its volunteers, organisations often treat people as difficult challenges to be overcome. Ironically, waiting until the last possible minute to get their agreement often makes this challenge a self-fulfilling prophecy.

Organisations and leaders are often scared to engage, because they think it means giving their audience extra time to object to decisions that need to be pushed through. But engagement isn’t about false choices, where people are asked if they support a decision that has already been made. It’s about involving them in the decision making process so that they understand why the decision needs to be taken. If there is a genuine choice between two options feedback from stakeholders is valuable; if there’s only one viable option, engagement means using a strong communications strategy to explain that honestly and persuasively.

At its core engagement should make people feel involved and significant. This is the lesson Brexit should have taught everyone by now, but which Theresa May and others still seem to need a refresher class in: if you don’t bring your audience with you, you’ll often find them working against you.