Jennings wrote:
http://tinyurl.com/4ylfops

Thanks for the replies guys.

There is a photo above. It isn't brilliant, I can do another if you
need.

The markings look familiar, but I can't place it. My dad thinks it's from
poor watering.

Personally, and I'm no expert (despite the hundreds of tomato plants that I
go through each year - I'm still learning, just on a bit of an over
enthusiastic route! :-) I would take off the branches that are affected if
they are low down ones, then top up the soil a little higher to make up for
it.

But if someone else has a different suggestion, I'd go with theirs not mine.