Could be Steve, is there any of the same discolouration on the leaves and stems of the plant?

I have a photo of a tom plant with blight on my photos page. Go to page three and it's on the bottom row.

It could be "bottom end rot" caused by irregular watering.

If however you think it is blight, then you must dig up and burn/bin all of the plants and don't plant any vine type veggies (cucumbers etc.) in that spot for at least five years. Don't put any of the soil or plant debris in your compost bin as the blight can live in the soil for quite a few years.

it looks more like blossom end rot to me, have the leaves and stems been affected ? are the toms in greenhouse or garden.?

Hi Tulsa, Blossom/bottom? OK I got it wrong! Lol ;~))