I had a couple of fruits that I aborted with BER , since then a bit of a problem with leaf miners but nothing too serious.

As the tomatoes reach full size they have developed a brown discolouration which leads to the pictured legion.

Any idea's?

Could it be sun scald, i'm guessing the plant only gets about 3-4 hrs direct sun , but that sun is quite hot. but the brown patches are on the underside.