I popped down to Linacre this morning to check on the Shags. There were still 3 juveniles on the middle reservoir.
Whilst there, I spotted a small flock of approximately 8 Long-tailed Tits flitting through the willows on the North side of the middle reservoir, and in amongst them was a Chiffchaff! This record is the first December sighting that I'm aware of, and therefore the latest ever Linacre record. Last year, we caught and and ringed a juvenile bird in November (see here), and there have also been October records in 2013, 2012 and 2011, so it seems quite likely that this species over winters in small numbers. Now we just need to catch a bird in January to prove it!