Poorly lawn

We have had so much rain here in Essex, ( ha ha drought!) and I have had a problem finding a dry spell to cut the lawn. I managed to do it yesterday as we had a dry morning for a change, but then I noticed these problems. We are on clay here and it takes forever to soak away after a downpour. The border edges are full to the top with water and there is something growing in it that looks like blanket weed. Green and fluffy/slimy. Also there are patches on the lawn that have a black mould/slime on the soil. I know these are both the result of so much rain but what can I do? The whole lawn area was piped and bore holes dug and filled with stones, before it was laid 40 years ago as we knew how clayey it was, but in all these years I've never seen it so bad. With more heavy rain forecast for the rest of the week here I don;t know what to do for the best.

I'd wait and see what happens when the water goes down and the rain is over. Most moulds simply shrivel up when the sun hits them, so you may find that the problem solves itself.

Thanks Alina, gooness knows when that will be as we've had rain again overnight and as I speak guess what --it's raining!