START OF MY BOOK - OPINIONS?

Not bad and I like the flow and atmosphere it has, but it didn't exactly grab me. Sorry. The first paragraph is interesting but going into the second just seems like too much description. It's a lot of telling, so work on showing those things so I can see it in my mind. Just try to find a balance of describing what's absolutely necessary while having the plot move forward. The third paragraph is where my interest peaks. I'm not sure what 'ancient' heart means though. Then, don't forget the why of it all. Why is he running if he's hunting? What's he hunting for in the middle of London? You mention 'I first saw her' but that's dropped immediately. That might even be a good place to describe what she looks like. If he's following a scent, is it perfume or her blood or what? Just paint exactly what's happening in the reader's mind. It's a good start but leaves me with a lot of questions. Good luck!