So apparently I've been running up hills all wrong!

It's my own silly fault, I'd misremembered something I looked up the first time I tried running, it was a while ago, and over time I had got it into my head that I should lean forward, focus a few steps in front of myself and just keep going until I got to the top. This, it turns out ,is really bad technique. In fact it's almost the opposite of what you need to do.  Here's a really good youtube video showing proper technique.