Whilst up to the elbows in muck and rubbish it seemed like a good idea to clean off a few more parts.  The surprise of the day was that, under all of the rust and old paint, the body of the Klaxon horn was nickel plated.  This is the front view.  The electric motor body was rusted steel before the application of a wire brush and emery cloth.

The back of the instrument.  Under the many coats of paint was the original maker's nameplate.

#172500A for those people who collect such things.