I guess you could do this if you have a dodgy starter motor, but I found it the best way to lock the flywheel in order to remove pulley bolt for changing cambelt or doing an HGF repair.
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*All mechanical suggestions and tips are purely for information only. I accept no responsibility for any damage to vehicles or persons as a result of any of my information. Consult a MG-Rover manual before attempting any repairs. Some repairs should be carried out by professionals only.