Extreme competitiveness, such as in the last Rule, can be one of the reasons why people become extremely sneaky and manipulative to get what they want. Of course, we can all be manipulative at times, but some people can be relied on to be sneaky and underhand as a first port of call.

I’m acutely aware that about a quarter of this book is about getting people on your side, and you could argue that’s a form of manipulation. My defence is that I advocate using behaviour which doesn’t disadvantage – and indeed often benefits – the other person. I’d call that influencing, not manipulating. As you know, I’m only passing on my observations of what works. However, it’s fair to say that some underhand approaches can sometimes work too. But when I talk about being manipulative, I’m really talking about using stratagems and ploys which take no account of the effect on the other person, and are often to their detriment.

Right, having got that disclaimer out of the way, what is going on with these manipulators? It would be impossible to list the potential – and often complex – causes of this kind of behaviour. The key thing is that these people have been conditioned by experience to believe that this is the best way to get what they want. And good manipulators, with plenty of experience, probably are getting what they want a lot of the time. The problem is that it can be very much not what you want.

These people have found a novel way of controlling you, whether it’s at work or in a relationship. You know they’re doing it, but you can’t prove it. They’ll deny it, and they’re often too good at it for you to feel that your boss or colleagues will believe you. They ask leading questions, they emotionally blackmail, they never accept blame, they try to convince you that you’re the one with the problem, they lie, they plant false information (literally, or in people’s minds), they deliberately thwart you, they have an instinct for your weak spots … A small-time manipulator is hard enough to deal with. A big-league player is a nightmare.

So how do you deal with them? For a start, don’t let them convince you that it’s your fault. You know this person is manipulative, so any suggestion that you’re being over-sensitive or forgetful or unreasonable counts for nothing. Learn to believe in your own take on the situation, and not theirs. Every manipulator has their own pet strategies – think through how to recognise them and plan your responses in advance. If they claim credit from you at work, start copying the boss in on emails that show otherwise (you can say you’re keeping them in the loop on a project). If they try to put words in your mouth (‘Don’t you think it’s better for the kids to go to bed earlier?’, ‘Isn’t that what you wanted?’), don’t get sucked in. Make it clear they’re expressing their view, and you’ll express yours.

Learn to say no to people who cajole or play on your emotions. Don’t justify yourself – you don’t have to. And ultimately, if you can, avoid manipulators like the plague.