Around my village, and all over the country, Horse Chestnuts (Aesculus Hippocastanum) have been having a tough time of it from leaf miner moth infestation. Around now, most of the leaves will have fallen to the ground, and if they’ve fallen onto your ground you may be thinking of leaving it, or moving it. For Horse Chestnuts, it might be worth moving it and burning it.
Perhaps earlier in the year you noticed the early browning leaves, curling up and falling far earlier than the other trees in the area. Maybe you noticed the conkers this year were far smaller and few in number. This is caused by the horse chestnut leaf miner (Cameraria Ahridella), discovered in the UK in 2002 and probably spread from Europe by cross channel traffic.
There is no cure for infestation at the moment, but the leaf miner moth overwinters in the leaf litter and removing this for burning or commercial composting will likely reduce the extent of the infestation the following year. Home composting probably doesn’t achieve the temperatures needed to kill this invading species.