"Adrian" wrote in message
...

If it's not a silly question, why did you stop in a position where he
could pull up alongside?

You can't actually prevent it.

I have been in the situation where I have stopped for a children's crossing
patrol and because I turn right immediately after the crossing, I am toward
the right side of the lane. A car pulls up alongside me on the right and
stops, straddling the centre line. I could only guess that she was using the
cyclist as a kerb marker :-(