The psychology of negotiating is hugely important, and the bigger and more important the deal, the more the other person is likely to be trying every trick in the book to get what they want from you. And that means they’ll be on the lookout for any apparent weakness – contractual, practical, financial or psychological. I should just point out that when I say ‘the bigger and more important the deal’, I mean to them. This might be an everyday deal to you, but it could mean the future of their small business. Or you might be happy with the status quo regarding bedtimes, but your child cares desperately.

Conversely, reaching an agreement might be more crucial to you than it is to them. Listen, you can’t assume everyone else understands the importance of win/win as clearly as you do. Even if they do, it might not matter as much to them. Suppose you’re one tiny supplier to the huge multinational you’re negotiating with. They don’t need you half as much as you need them, so why would they care whether you come out feeling good? They’re up for a deal that works for them, but they’re not going to cry into their pillows if they have to go and find another supplier instead. You can’t count on them to be looking for a win/win deal.

OK, take your child’s bedtime. She doesn’t care how you feel, except in as much as it will get her what she wants. She knows you’ll always love her no matter what. So although you have the authority to impose the rules you want, she can make you feel horrible about it. She can shout and rant, or sulk, or emotionally blackmail – if she’s a normal child, I’m sure she’s adept at all of these when she feels her back’s against the wall – so you’ll feel bludgeoned into making concessions unless you’re extremely strong-willed.

In all these scenarios, the other person has the potential to walk off (or storm off) and leave you feeling worse about it than they do. Not reaching an agreement might be their Plan B, but it’s your Plan Z.

The one thing you must never, ever do is let them see that you’re scared, worried, anxious, nervous about not finding any centre ground. If they can see they’ve got you on the run, that no deal would be worse for you than any deal, they’ve got you over a barrel and I can’t help you. No one can. They can demand anything they like and threaten to walk away if you don’t agree, and you’ll have to say yes or give into a deal that really doesn’t work.

There are always going to be times when you need agreement badly, and are worried about what will happen if you don’t reach it. You can’t always avoid the situation. What you can do is maintain a calm and unflustered front, and appear keen to strike a deal but prepared to walk away if you have to. You know it’s not true, I know it’s not true, but for goodness’ sake, don’t let them know it’s not true.