Help identifying farmland bird?

Saw a smallish brown bird on top of a scrubby hedge next to a stream through some farmland today in the south west of England. It was larger than a robin, and had some colour difference between the head, throat, and body, but was unable to get any closer due to the stream. The call was a short trill that didn't really change in pitch. 

I took a video but my phone camera isn't great so not sure if the image will help but possibly the call will help. 

Probably missing something really obvious!