Don't know if anyone has said this yet but I would try directly feeding the injection pump with good clean diesel or oil/kero mix - the kero would ignite better. Take the pipe off from the filter and the injection pump, empty its contents then screw it back onto the IP, with a small funnel or something pour diesel down the pipe into the IP, leave it a little slack so the diesel goes right to the IP and lets all the air out, now try and start it, if it starts keep feeding it diesel and keep it going for a bit to warm it up. The connect it all back up and fill the filter with diesel too. Then go get some PETROL in there. If you just change the tank contents you have about a mug or more of diesel in the filter to contend with and all the pipe work.
Are you sure your glow plugs are working, your engine will simply not start without them, and are you SURE that diesel is going up to the injectors? Even with a lot of veg, if everything was working right it should start.