I've just been out to the garage and check, in the second photograph the wheel isn't attached.
The collar (the part with the text on it) should be the same distance away from the steering wheel as in the first picture, so this is why it's not locking.
Try this. Put the wheel one and turn it to make sure you can turn the front wheels. Holding the wheel in place, try and slide the collar towards the steering column. I'm guessing the collar spring is okay and it goes to full extension off the column by its appearance in picture 1. I know this sound stupid but has anything got inside the tube that goes the column stopping it go on fully?
