In case anyone else comes across this..

When I started up the game it skipped through the opening cutscene etc automatically and in game the trigger was held down (firing constantly until the gun jammed) and my plane dived down left and pressing WASD made no difference. Obviously unplayable.

I plugged in a Logitech Extreme 3D Pro and unplugged my X360's wireless receiver (the controller itself was off anyway) which made a little difference: I could use the joystick to counteract the dive/roll but not go the other way and the trigger made no difference.

I went into Device Manager and disabled vJoy, rebooted and ta-da! It now works fine.

I find the keys easier to use on the strafing runs though.

Edit: Sort of spoke too soon. Fire button still appeared to be stuck on but the default mapping has shoot mapped to an axis for some reason. Remap the controls and all is good.