I think I had him approach me on London Road opposite Sainsburys one evening earlier in the year, I'd forgotten about it until I read this post but the description fits.
He approached me just by the crossing and asked something like if he could borrow my mobile phone (I was'nt using it at the time-he just approached and asked this).
When I shook my head and kept walking he followed me a bit until we reached the Barbers shop and flats set back from the road he was cussing and yelling abuse at me but I kept walking and he gave up-
It was pretty scary at the time if I'm honest but luckily it was a busy time of day (around 7pm) and there were lots of people around I think thats why he gave up and backed off.