I know not how rare it is to spot a Goosander and 10 chicks in summer, but I personally think it deserves a mention since it is a first for me at least, and they disappear from the Valleys in around April. Also 2 adult dippers with 2 chicks @ Sgwd Yr Eira.
Glamorgan Bird Club 
Rare enough! Even though they occasionally breed in the County, there was no breeding confirmation in 2013 although they bred in the previous three years. In 2012 they bred on the same river as your record! Great record of yours though.