ANTIQUE  ROLLTOP / CYLINDER OR TAMBOUR DESKS - 1780 on

Both terms are used to describe any desk with a superstructure enclosed by a half or quarter round sliding lid which disappears into the structure when lifted. A cylinder top has a continuous smooth surface; a tambour is slatted. This type of desk originated in France a little earlier. 

BASIC STYLE
Early examples (about 1780-1830) mostly with a base as a lady's writing-table,  but often larger and sometimes with extra lower drawer on each side. Frequently an upper cabinet or bookcase above. Super-structure fitted with small drawers, pigeonholes. Sometimes the inner writing-surface pulls forward as top lifts. If quarter-round (most common type) the flat shelf at the top bordered by a brass gallery. 
Pedestal versions (mostly tambour) about 1870 onwards. Similar interior fittings; inset leather (later 'imitation') writing-surface. Flat top above bordered by low wooden gallery Tambour sometimes serpentine instead of quarter-round. At all times lid on both types lifted by two (occasionally one) knob's) or handle(s) fitted at its base. 

CONSTRUCTION
Tambour: Constructed of large number of horizontal laths or narrow moldings, laid close together, their flat sides glued to a piece of stiff fabric. Note: These are often damaged - especially if the fabric and glue have dripped out - and difficult and expensive to repair. Do inspect the tambour carefully and open and see it several times to make sure it functions. 

Cylinder: Always veneered: on base composed of many long and narrow angled or grooved pieces of timber, planed on outer edge to provide a smooth surface. Both types slide in grooves cut in sides of superstructure. 

VALUES
Very large numbers of these desks were mass-produced for office use between the wars (though some would date them pre-I914). Characteristic features are horizontal wooden pull handles on lower drawers, rectangular metal label frames (either with integral pull or separate small turned knob) on inner drawers, paneled back to recess and simple curved apron at front. 

Plywood drawer linings would be an instant giveaway.

Early writing-tables rare and correspondingly expensive: even Edwardian reproductions fetch four-figure sums. Victorian pedestals relatively less; only the meanest half-pedestal or coarsely-made inter-war pieces found for three-figure sums.