Hmm... Come back from a trip to Spain and a week later this turns up. Great find by Kerry Harrison. Needless to say a first for the Peterborough area if accepted.
In the field this bird appeared a lot greyer than if does in these photos. Yellowish tones were virtually lacking being only detectable on the upper rump and back. The song sounds right but this bird does habitually add a few notes to the end of the typical song.