On behalf of Liz who sent in an email:-
Size and shape rather squat / roundish. Seemed to have short legs, very little tail.
Beigy-grey with bright green patch visible on back as it flew away.
Seen by neighbour several days running simply sitting on lawn for several minutes before flying way. I had a brief glimpse there yesterday and thought it could be a partridge.
This morning it was in my garden and I saw the flash on it's back as it flew away. This made me think Jay.
I'd love to know what it really is.