One of those nights where everything that can go wrong did go wrong. Must have bumped the mount at some stage so my polar alignment was way off.
I used the PHD2 drift align tool to tune things a bit and before I packed up I took 2 images of M20, The Triffid. One 5 minute and one 10 minute exposure at iso1600 to check the tracking/guiding. Seems pretty solid, for now.