Harriet Walker: 'Friends are... people who'll help you clean up in the morning'

Years ago a rather cynical teacher pointed out to me that we make friends only with people who happen to be nearby. Ever since, I have fretted and fussed about whether we're all just flubbing about with people we hate just because we don't want to be lonely.

You have to take friends where you can; sometimes you get lucky and, as well as having things in common, you also like each other. It isn't the same as a romantic partner, because you can actively search for and discard them much more easily, and with much less of a reason. But if we realised just how flaky some of our friendships are, the world would implode.

"I'm not going to be chums with her on Facebook any more," declared my sister over lunch recently, of a girl who bullied her at school. "I'm going to delete her. She never does anything interesting anyway."

"Keep her," I suggested. "That's the point of being Facebook friends with people you hate. They make you feel better as their lives are so awful."

"Schadenfreunde," said my dad from behind the paté, and we all groaned. "I thought that was quite good for someone who doesn't speak German," he protested.

I went to a drinks party before Christmas which was stuffed full of young male barristers; they looked like cherubs trussed up in suits, their curls spit-flattened, eyes brightened with gin. "How strange," I thought, "when the friends of friends exemplify exactly why you shouldn't be friends with the friend."

"Walker," exhaled the host, "I've made you a Negroni." I accepted it in the style of someone who knows exactly what a Negroni is and is very at home conversing with a tweed jacket worn over jeans. "It's only baby measures," he continued, "but no doubt you'll be pie-eyed by the time you finish it." "How well Henry knows me," I thought, satisfied that there was still substance enough to our acquaintance.

A week later, I found myself watching helplessly as 18 Argentinians I had never seen before arrived at my New Year's party. Seeing as I'd managed to fill my party already with friends – Schaden and otherwise – I decided they were an unknown entity who might cause untold damage. As I closed the front door on them, I knocked over a pot plant and made the biggest mess of the night. "Well," I rationalised, "at least I have some real friends to help me clean this up." Sure enough, as dawn broke, I blamed the soil-soaked carpet on the strangers and thanked my pals effusively as they scrubbed it. A good friend is worth their weight in gold, after all.