Confused white girl

Grind to a halt on the tube. Some smartly dressed Indian people start talking to me; they are running late for a wedding and want to know the quickest route to Victoria.

'Our oldest auntie is a total stressbucket,' one of them says. 'She's the only one organising the food and there are so many people coming.' 'I know,' says another. 'Normally it's a case of too many chiefs and not enough Indians.'

I think this is quite funny, but I am not sure if I am allowed to laugh. Would it be racist if I laughed, even though they made the joke? It's very confusing. I was brought up in 1980s Cumbria, where the only ethnic minorities ran the takeaways, serving deep-fried pineapple rings and warm bottles of dandelion and burdock. So it was a bit of a culture shock when I moved to Elephant and Castle in south London, where my pasty face was in a minority.

It was there that a would-be mugger followed me home. He happened to be a big, black hulk. He tried to steal my bag, but did not count on my vice-like grip and Hammer Horror scream (I didn't know I had these gifts until he grabbed me).

I became edgy walking back from Elephant station. I would eye the black boys in the market eating jerk chicken and nodding to No Woman No Cry with fear. About a month later I was striding home, loaded with shopping, when I heard a familiar stomping closing in on me. I started to sweat. He had returned to finish the job. I put my shopping on the pavement, praying he would just walk past me. He didn't. He stopped. I grabbed my keys to use as a weapon. I looked up.

Gazing down at me was the dark-skinned angelic face of someone who could have been in a boy band. A choir, even. He saw the terror in my eyes.

I decided there and then to stop being such an idiot. Yes, the man who tried to mug me was black. But that didn't mean all black men wanted to steal my bags. Hell, some wanted to help me carry them home.

So I'm definitely not a racist. But I am still sat on the tube, wondering how to show I'm not a racist. The Indian friends are still laughing at their joke. 'Oooh, I like your dress!' I say.