Thanks for that Hazel. Great phots. Not a shape I know!
Note #1 - Apart from the engraved birds, the verticals & the curved portions of the neck & stopper appear ground & not fire-polished afterwards. That would indicate a substantial age I suspect.
Note #2 - Have you noticed the small scatch marks on the inside of the bottle lip. Usually they are matched on the stopper. I have seen them used as a pawnbrokers mark so the stopper matches the bottle.
Ross