Tomato Plant Leaves Turning Black?

You may have blight- caused by a fungus in the air. it likes damp warm condition and was bad last year, it is the same a potato blight and could have caught it from nearby potatoes?
Burn all the dead leaves etc. I changed my soil for this year - hope it goes OK.

I lost some last year from the overly wet weather! (FLOODS) I took off ALL the leaves EXCEPT the very top and they lived.