On further thought I take your point.
I still feel that the original poster was correct in giving way to the car going straight on. That car had priority, as turning in front of it would have meant crossing its path.
Sddsdean's comment in the very first answer is correct. It depends on how soon the second car followed.
If it was immediate, then the driver could feel he or she had priority aswell.
However if there was a delay, then the point several of you have made would be true, that the turning car 'had the road', and the car on the side road should have to give way to the car on the major road.
That may be why the police agreed with manfatholl