Little olive-brown egg

Connie was very excited by something in our hedge - a long Chamecyparis along half the boundary of the the house garden She went in up to her tail tip. Thought I heard faint sounds but nothing definite - and I saw nothing unusual.

The next day, passing the same spot in the hedge, I found a lovely sage-coloured green egg! When cleaned and dried it looked more olive-brown. Unusualy for September the 14th ?.

Here it is beside large hens' eggs:

It measured 4.5 X 3.1 cm

Looked to https://www.woodlandtrust.org.uk/blog/2016/05/identify-egg-shells/ to identify it 

It seems to match a pheasant's egg best among those shown there. The pheasant. it says, lays between April and June so perhaps it was there for several months - or some Pheasant has got its timing all wrong. There were pheasants coming and going earlier in the year so perhaps one of them left this behind. Interestingly, it was at just the spot in the hedge where a Leghorn hen I once had (Atilla the Hen - old DroimAnUan blog posts) used to hide her large clutches of 13 eggs years ago.