Twit, twit, t - who?

Since my last post (hmm again some gap) I have been twittering.
When I started, I thought I'd just let any Tom, Dick or Harry see what I was writing. As time went on, the only people who seemed to want to follow me seemed to want me to look at their tweets and, well, buy something. They were commercial organisations using Twitter as a way of reaching - well - anybody really. I didn't buy anything, turned my twitter account into a private one so prospective followers would need my permission. All went quiet, except that I managed to keep on follower whose identity is completely blank, so I put this down to being a system bug. Well, as an IT professional, of course I would.
Then last week I had two new prospective followers. A BBC Norfolk journalist and a Norfolk hospital. Spot the link? Yes, my resume does say I am in Norfolk, but I think it must be hard to track down information like that at random. My link to a Norwich church seems relevant, but to a hospital?
I'm therefore not sure what makes people - or organisations - try to track people down on Twitter.
I'll still carry on twittering, however!