In the UK, can a police officer request my name and information if they do not suspect a crime is being committed?

Me and my girlfriend were waiting outside a bus-stop in a rural area quite late at night (minding our own business, sat down and listening to my iPod through some headphones), when I noticed an old lady staring out of her window at us.

I didn’t think much of it, until a few moments later, a police car arrived and two officers got out. They seemed surprised, but then informed me that a homeowner had made a report of ‘youths loitering around the houses’.

Rather odd as we’ve just been sat here I responded and we haven’t seen anyone. The stated that they had no reason to suspect a crime was in progress and that we were no under arrest (they went on to say that we seemed like ‘perfectly decent people’), and then gave their names. They then went on to ask us for our names and details ‘just as standard procedure.’

We obliged, and provided the information, and they apologised for the trouble and left. We caught our bus a few minutes later, and I didn’t really think much else of it, except that I felt quite sorry for the woman who was obviously scared that teenagers were going to vandalise her front garden or something.

But it got me thinking—the police stated that they didn’t suspect a crime was in progress, so why did they ask for our information? Is that legal? Could I have refused, and if I did, what would have happened?

This is in regards to the UK (in specific, England), but if you know the answer for elsewhere in the world, why not share it anyway—it’s interesting to compare.