Moved into our new build house 7 years ago, including standard square-of-grass garden. For years it was horrendously clay/soggy/poorly draining/flooded. But I planted and mulched and planted and mulched and I think I might have achieved moist well-drained soil!? I always thought it was a myth, but it's become easy to dig and feels good! Loads of worms. I can't grow anything that errs on the side of liking well-drained soil, but other than that everything is very healthy with the nutrients from the clay. So, just wanted to offer some hope to any keen gardeners who have just moved into a claggy clay new build.