Having watched the Bittern go to roost for a couple of nights, (and using warden's privilege) , I put my "stealth cam" in an area which I hoped might catch the bird on film. I have been incredibly lucky to point it roughly in the right direction and avoid most of the reeds!
Further footage is on the Montgomeryshire Wildlife Trust website, (thanks to Tammy!), and shows prolonged preening, and a flypast by the noisy neighbours.
P. S Hope this works!!