I have a number of writing slopes in what I would loosely describe as a collection :).
This slope is the largest I have at the moment anyway it measures approx. 500 mm 20 inches x 250 mm 10 inches and 175 mm 7 inches.
The top and front are burr or burl (depending on where you are) Walnut with the sides and rear being the cheaper Walnut.
As you can see the ornate brassware has been removed some of which was inside the box when I acquired it. The brass ware had been replaced by green paint I have no idea why but I have removed the paint and plan on replacing the brass when time allows.
The inside of this slope is quite clean and really needs a fresh skiver fitted.
One of the unusual things about this slope is there is a small handmade brass ring on each writing surface with a small ivory or bone pin with a thread on one end that screws into the ring to allow opening of the flap. it is lying in the small compartment in the bottom left of the picture.
My research taking into account of the size and materials used along with the type of construction leads me to think this slope was made early in the 18th century.