Abstract: An anti-theft device for a motor vehicle comprises a steering wheel 10 having a centre boss 12 mounting the steering wheel onto a steering column 11. The boss is slidable axially of the steering column between a first position in which complementary splines 14/15 on the steering column and boss engage each other to secure the steering wheel and steering column for co-rotation and a second position in which the splines are disengaged so that the steering wheel is freely rotatable on the steering column. A lock 21 can secure the steering wheel in a selected one of the first and second axial positions by engaging in a groove 17 or 18 in the steering column.