Get rid of the larvae that are probably in the lawn they're trying to get at. Lay a sheet of black plastic on top of the grass in the evening, preferably when the weather is mild, not freezing cold. Lift it first thing in the morning - if its leatherjacket grubs, you should see them on top of the grass, beneath where the plastic was. The other possibility is chafer grubs, but its more likely to be leatherjackets. There are some chemical drenches that profess to kill the larvae, but I'm not sure how effective they are - there is a nematode treatment which can be watered in, but its too cold to use it at this time of year, more info in the link below

https://www.rhs.org.uk/advice/profile?pid=651

Improving drainage and good general lawncare techniques should help to deter further infestations, so aerating the turf regularly if its pretty wet will help.