Restoring an old, french woodburning fireplace

Hi there,

I'm trying to restore a wood burning fireplace of a type I've not come across before.

The fireplace is fairly small, with a marble and plaster mantel. There is no hearth to speak of. All that remains of the grate is a flat, metal plate that sits about an inch of the ground with an air space underneath. A retractable metal screen can be lowered by degrees all the way down to completely cover the fireplace. It is a 19C fireplace, we think from around 1840. There are 3 in the house, which is in Pyrenees-Orienthales.
Do you know what sort of grate and hearth a fireplace like this should have? Should there be an ash pan a fret or even a dog grate above the base plate?

I'd be very grateful for any advice you might have! I've attached a picture...

Many thanks!