How does facebook know this?

[OhBuggerandArse]

Facebook is insistently telling me that I should be friends with someone who I do in fact know, but who is not friends with anyone else I am friends with on FB and shares no institutional links with me as far as I am aware. It must be more than chance, as he keeps popping up - how on earth can this work? Are they just in cahoots with the Google guy who goes round with the camera seeing what everybody's up to?

Have you ever had email contact with him? FB can search your email account (with permission) so if you or he has allowed this, it will know that you know him.

My FB account knows I know people and it took me ages to work out that this was how.

Ah, I suppose that might be it - but I've never let FB go through my email, and I'm not sure he would have - he's not very geared towards that sort of thing in fact only has one friend on FB anyway! A good starting point, though.