Had a look at the blog and saw Rob mentioned the dusky-cheeked Tree Sparrow.
Theo drew attention to it the day I was there, it was on the playing pitch behind Anton's. It was difficult to pin down as the 'flock' was moving around a lot. I fired off a few shots as I thought it was the best view we were going to get of it. We also considered a hybrid, on the poor views we had, but it appears to be just a darker bird compared with the other Tree Sparrow.
I won't waste your time with the Hooded Merganser shots I got.