Uneven ground

Q There’s a sunken hollow about a metre in diameter in the middle of my lawn. It’s always damp and muddy, and I’ve no idea how to get rid of it. Can I level it out and make my lawn flat and even?

A It’s probably at a low point in the garden so water runs off into it. It might be worth using a spade to dig down to investigate, as there may be an underlying cause such as a hardpan (an impervious layer, often of clay) which will need breaking up. Then you can top up with topsoil (or a layer of subsoil first if the hollow is more than 40cm deep) and compact with a roller before seeding with grass.