The secretaire en portefeuille is an antique desk form which is usually mounted on rollers at the end of four jutting legs.
The legs in turn support what looks like an oversize vertically mounted wooden pizza box.
This is a cabinet a few inches thick, with barely enough space in it for the raised desktop surface and a few pens and sheets of paper disposed vertically.
[1] The secretaire en portefeuille is much like a fall front desk which has been reduced in depth to a bare minimum.
By its mobile nature and its relatively light weight it was sometimes used as a fire screen desk.