Thanks everyone, really interesting to hear how each of you has tackled this apparently universal issue!
Hadn't thought to check whether it's vertical or not - to my shame I got someone else to put it up for me and just assumed they did it right! The rest of the holds are fine so I'm fairly sure it's right...
I had felt that a dusting of chalk maybe did help a bit, but I'll also give it a good clean to see if that makes a difference. Intrigued at the idea of having damp hands - I kind of suspect that'll just end up with me in a heap on the floor even quicker than normal!
I'll report back in 5 years as to whether I'm hard or broken. Pretty sure it'll be the latter but we'll see.
Maybe the take-home message is that you can't make a beast without pretty regular struggle and frustration. Which makes sense.