Spongy, wet lawn

Hi (new member!)
I've just moved house and have inherited a dreadful clay soggy garden. Looking through message boards I now know how to combat the borders, but the lawn is laid on this same horrible clay gunge. When I tread on the lawn it seems spongy and seems to hold a lot of water. I have no idea what it will be like in summer, possibly crack when dry? Luckily it's not a huge garden, so hoping it's something I can resolve myself! Any ideas?

 

So far as I know, I believe a wet, soggy lawn to be indicative of moss and thatch - dead grass. So what your lawn needs is scarifying.
Take a look at this site, it's a mine of good tips.
http://www.lawn-care-tips.co.uk/lawn-maintenance/index.htm