It decided to just go down and stay down. Hmmm. After some digging around I found a post from Varescrazy mentioning the earth cables on the drivers side door hinge, so that's first port of call. The motor is still working and it won't go up from either passenger or driver side so it seems to be lacking an earth. I also found the circuit board posted by Bernievarian, the worst case scenario is to put 12V through the pins with a spare battery, get the window back up and then disconnect it. Will see how it goes tomorrow, thankfully its not raining here tonight...