Had one of those mornings when I thought everyone else in the carriage must know the same people, or have been to the same party, or work in same office.

It was the mention of tofu that did it. I knew I'd heard tofu being talked about in the same context somewhere before...

"There's no way tofu should have been on the list. It's a definite non-essential item," said woman, sitting diagonally opposite.

"Well, it could be essential for vegetarians..." said her friend.

"But, if there's only one vegetarian and it means everyone else going without coffee - which is definitely essential - then someone's got to give".

I knew I'd heard, or possibly even had, that conversation before but couldn't think why or with whom. So, I listened on.

Perhaps, they had the same builder - who came to put up shelves and single-handedly turned on its head the image of the builder who sits around eating bacon sandwiches, while pondering the problem of how to build the thing, whatever it is, oblivious to the fact that his trousers are too small and need a belt, by getting on with the job, looking more like the Diet Coke 11.30 appointment builder and shunning the bacon butty in favour of aforementioned tofu.

"She needed chocolate as well - perhaps she was going to make chocolate-coated tofu for everyone."

"I doubt it. Anyway, I knew she'd be the first to go."

"She did agree to take tofu off the list in the end," joined in the man sitting opposite. "I thought they'd keep her and get rid of the older one. After all, she was very attractive!"

The penny dropped. I hadn't been to the same party, and didn't share the same friends, or builders, as people discussing the tofu issue so avidly - but had been sitting in front of the television, at the same time, and watching the same channel.

Big Brother - is watching you. Self and, as it turned out, almost entire commuting fraternity had been watching Big Brother.

Apologies to anyone who hasn't been watching - but suffice to say the issue of whether a woman called Sada, or Sade, or some equally earthy name, should be chucked out of the house or not, because she liked tofu, was enough to sustain almost an entire programme and keep everyone talking the following week.

"I didn't think she'd last to the end - but I was surprised she was the first to go," agreed one of the two women, whose original discussion had sparked interest among everyone else.

"What do you think?" she asked me.

"Oh, I don't like tofu either," I said.

"I meant, do you think they were right to get rid of Sada?"

By this time we were nearly at Victoria. I got up and started walking towards the door and happened to pass blond athletic man from Hassocks, who'd apparently been sitting in the seat behind me.

"So," he said. "You're not a fan of tofu or people who eat it? And I'd been thinking how much Sada had been reminding me of you and how I'd definitely have kept her in the house!"

Does that mean he thinks I'm an irritating control freak? Or is he like the man opposite who thinks she's attractive and wanted her to stay?