Hi Chris,
Had similar problem myself, it needs a new ignition switch which is a round unit which fits behind/ underneath the ignition key. A little fiddly to get out as it would be ideal if one were a contortionist. When I did mine I did not take the drivers seat out and it would have been much more comfortable to have done so. take the stiffish trim panel which is clipped in under the dash and at the pedals. One then puts a couple of plump cushions on the floor and stretches out looking at the switch from the back. Not too hard to get off, disconnect the battery and just remember which wires went where.
Regards,
Charlie