If you havent a key, or lock is knackered the only way is.
Remove the steering wheel, column stalks and the spring and locking washer from in front of the column bearing. WATCH THIS SPRING, IT WILL HAVE YOUR EYE OUT!
i held one of my old t shirts over the column shaft and spring whilst i prised the washer off. take the fusebox cover/lower tray off, bottom ign cowl off, remove the bolt clamping the ign casting to the steering colomn. then prise the casting off where the bolt was, not easy and you might damage the top cowl. but it can be done. u aint stealing it r u???
