Great Blue Heron - Stanton Park Swindon.

Hi I suspect what you saw was our own Grey Heron as there are no sights of a Blue Heron anywhere in the UK for the recent past. It is the N American equivalent of our Grey and at 8pm perhaps the light made the sighting deceptive in fading light,

I would suspect grey heron having looked  at the likelihood.

It could be the evening light and shading has tainted the heron plumage, something I see quite often when out and about with many species, at various times of the day.

While I agree with that it was most likely our old friend the Grey Heron just because a bird is not on a rare bird sightings page does not mean the original poster did not see a Great Blue Heron. Somebody has to be the first to see the bird and then that someone has to report it to the the relevant site if they know such things exist. I subscribe to several such sites and realise that often rare birds we know of are not reported. Just saying we are often quick at discounting sightings because they are not on certain sites. After that little rant I still go with the Grey Heron suggestions they can appear to be in so many different shapes and colours according to light

I would bow to the greater knowledge of the readers. Shame it got spooked as a photo would have helped. It was a magnificent sight. Keep a look out if in the area.. it still could be as Seaman says.