While the numbers of Dog People frequenting Clissold Park has grown enormously over the past few years, one of the things that hasn't changed is their inability to 'see' normal humans. I have always been able to walk amongst them, seemingly invisible, without so much as a glance. I could have marched into the middle of a group of them and emptied a bag of Winalot on their heads and they wouldn't have noticed.

This week, because our neighbour is poorly, I've been walking her dog most days (breed? Er, it's a little brown dog that looks uncannily like Robin Smith the late Labour MP) and today we ventured into the park. I wasn't in twenty seconds when two Dog People approached me, smiling in a strange friendly way.

"Hello!" one of them said. Was she talking to me? I must have looked startled.

"He looks like he needs a good run!" beamed her friend.

"Aren't you going to let him off his lead?"

"He's very friendly!"

Their eye contact was unbearably intense. I didn't dare let him run free yet, I said. But if I let go of the lead perhaps I would become invisible again. Most likely the effects of the dog wear off over time. Luckily I was pushing a pram with the other hand and my son was able to get me out of danger by crying.