Froggie? Went a Courting?

Observation - Froggie? Went a Courting?. Description: Very loud call noticed from some distance away. This link is for the movie which I have put on You Tube. I do not have a clear photograph. The 'Amphibian' appeared large and like nothing I have seen before.

Very loud call noticed from some distance away. This link is for the movie which I have put on You Tube. I do not have a clear photograph. The 'Amphibian' appeared large and like nothing I have seen before. The call you will hear on the film was being answered by another softer call, from two seperate locations by unseen responders.

http://www.youtube.com/watch?v=X2YWgDB9ykM

This was on a very Sunny day with some cloud cover in a pond adjacent to Bodiam Castle in East Sussex England.
I would describe the habitat as fairly open, grassland / parkland with both free running open water nearby, including the Rother River and that the pond the animal was in was populated by lots of reed / weed and was not fast moving at all.