Q.Grass Is Always Wet With Damp Patches
It’s been like this since we moved in but after several days of glorious sunshine I’m still surprised to find grass is wet under foot ( it never pools just stays wet). I dug a small hole down about 15cm (see attached picture) where I seemed to hit a layer of gravel with sand on top of it. The soil under the grass is very dark and wet and feels like you could mould it like clay. Is there anything I can do to reduce how damp it is.

Certified GKH Gardening Expert
This could be a septic, sewer, or water leak. If this stays moist without drying out then the only solution will be to stop the source. This will probably require the help of your local authorities on the matter.