Strange duck-like noise in reedbed -- can you ID?

Question

Play this audio clip 
 We heard this at Middleton lakes quite recently and can't match it to any of the birds we actually saw there, but whatever it was was completely hidden in the reeds.

TeeJay · Accepted Answer

I think it's probably a Marsh Frog. It's a non-native species which has been introduced to the UK and can certainly be found in wetlands in SE England like Rainham Marshes and the North Kent Marshes. It looks like it's found its way up to the Midlands. 
 Take a look at this YouTube VIDEO

Seaman · Answer

Certainly sounds like Marsh Frog,we sometimes hear this at Top Hill Low reservoir near Driffield in East Yorkshire