The Fir cone- a sign of clear vision of what is beyond and yet to come. It also opens when sunny and closes when wet. The following link is to an old story about a mouse and a fir cone.
Modern Woodpecker...keen ornithologist ?
Victorian Gothic by A.Kendrick & Sons. It has a bat perching on the top of the knocker. Bats area symbol of rebirth and of being very aware of your surroundings.
Dragon- to see clearly and a protector of the home.
Doctor's Knocker- Early Georgian and was designed to identify the Doctor's House.
Victorian Hand 1890's.
Looking through the prices and designs of knockers I found that one old knocker that I gave to a friend 20years ago as a house warming present is now worth £600 ! I wonder if they still have it ?
There are quite a few sites for knockers on the web but this appears to be a good one...