PETROL/GASOLINE IN A DIESEL CAR. I put a 50-50 mix in ours and this is what happened

So its early in the morning and Ian is on his way to work when the fuel warning light comes on. Not really thinking about what he is doing and just going through the motions he stops in a our local garage and starts filling it up. Its not until he has half filled the tank that he realise's the mistake he has made. This is the story of what happened.