I recognised later blight in some of my GH toms from your description, Dovefromabove, in a previous thread, took the affected leaves off as was advised and the crop was just as good as previous years. Without going out side to count there were about 6-7 plants in a bed so couldn't be moved, in fact the other 6 plants due to space couldn't be moved either I had fruit ripening from about mid July possibly sooner, Christmas grape was the first along with a striped zebra variety.
I've found each year seems to throw up different challenges, last year it was BER, red, yellow pear and the cherry varieties I grew seemed the only one's affected and these were grown in pots. It was put down to irregular watering and that some varieties are susceptible to BER. Grew red pear again this year and they were fine but I changed my watering habit and put gravel in the tops of pots to prevent evaporation.
A must this year is to change the soil in the GH bed.