(via Jeny Heard) Saturday 11th December - I was north of Penarth-Sewerage Works sitting in the up-ended boat seat at about 1p.m. when a bittern flew up river. From its colour, size and flight I am sure that it was that. I was not able to see where it went to from there. A search of the pools at Penarth didn't reveal any more.
Sadly due to a computer 'glitch' I only received this email yesterday, but it is still worth keeping an eye out anywhere where there is open water, for one of these magnificent birds. There's no reason why it wont still be hanging around!