If you look at the leaves of this tree you will notice they are brown unlike the others trees in the churchyard. This tree has the disease leaf blotch
Leaf blotch is an infection of the leaves of horse chestnuts caused by the fungus Phyllosticta paviae (syn. Guignardia aesculi), which causes irregular brown blotches, often with yellow margins. You're most likely to see attacks in summer.
The fungus was introduced accidentally into the UK from North America in the last century.