This is how my tomatoes looked just a few days ago.
This is how they looked today.
This is tomato blight or Phytophthora infestans.
Tomato blight, like potato blight, is a fungus which can spread rapidly by air or water in both the foliage and fruit of the tomatoes.
Blight seems to appear mostly in wet and humid conditions and outdoor varieties suffer more than greenhouse varieties.
In my case I have the same varieties both inside and outside the greenhouse. Only the outdoor plants seem to have been affected so far.
Whilst I have attempted to strip any foliage and plants as soon as blight was noticed, this was not enough and the fungus spread quickly through the entire crop. I am left with little option other than to consign the entire lots to the bin (not the compost heap). You cannot even pick the fruit quickly and leave to ripen as it soon rots as well.
To control blight without chemicals, it is best to operate a crop rotation plan and remove any infected foliage or fruit as soon as noticed.